HK1159850A

HK1159850A - Organic tandem solar cells

Info

Publication number: HK1159850A
Application number: HK11114089.0A
Authority: HK
Inventors: R. Forrest Stephen; E. Lassiter Brian; Wei Guodan
Original assignee: 密歇根大学董事会
Priority date: 2008-09-26
Filing date: 2009-09-25
Publication date: 2012-08-03

Description

Organic laminated solar cell

Cross reference to related applications

This application is based on and claims priority from U.S. provisional patent application No. 61/100,583 entitled "Organic Tandem Solar Cells" (Organic Tandem Solar Cells) filed on 26.9.2008 and U.S. provisional patent application No. 61/118,529 entitled "stacked Organic Solar Cells containing CuPc and SubPc as Donor Materials" (Tandem Organic Solar Cells Incorporating CuPc and SubPc as Donor Materials) filed on 28.11.2008, the entire contents of both provisional patent applications being incorporated herein by reference.

Joint research protocol

The claimed invention is made by, in the name of, and/or in conjunction with, participants to the following university-corporation joint research agreement: the board of The University of Michigan (The Regents of The University of Michigan) and Global optical Energy Corporation (Global Photonic Energy Corporation). The protocol was effective at the time and before the claimed invention was made, and was made as a result of activities undertaken within the scope of the protocol.

Technical Field

The present disclosure relates generally to organic tandem solar cells. Also disclosed are methods of making these devices, which may include at least one sublimation step for depositing a squaraine compound.

Background

Optoelectronic devices rely on the optical and electronic properties of materials to electronically generate or detect electromagnetic radiation, or to generate electricity from ambient electromagnetic radiation.

Photosensitive optoelectronic devices convert electromagnetic radiation into electricity. Solar cells, also known as Photovoltaic (PV) devices, are a class of photosensitive optoelectronic devices that are particularly useful for generating electricity. PV devices, which can generate electrical energy from sources other than sunlight, can be used to drive electrical consumers to provide, for example, lighting, heating, or to power electronic circuits or devices such as calculators, radios, computers, or remote monitoring or communication equipment. These power generation applications also typically involve charging batteries or other energy storage devices to enable continued operation when direct illumination from the sun or other light source is not available, or to balance the power output of the PV device according to the requirements of a particular application. As used herein, the term "resistive load" refers to any power consuming or storing circuit, apparatus, device or system.

Another type of photosensitive optoelectronic device is a photoconductor cell. During such operation, the signal detection circuit monitors the impedance of the device to detect changes caused by absorption of light.

Another type of photosensitive optoelectronic device is a photodetector. In operation, the photodetector is used in conjunction with a current sensing circuit that measures the current generated when the photodetector is exposed to electromagnetic radiation and may have an applied bias voltage. The detection circuitry described herein is capable of providing a bias voltage to the photodetector and measuring the electronic response of the photodetector to electromagnetic radiation.

These three types of photosensitive optoelectronic devices can be characterized according to the presence or absence of a rectifying junction, defined below, and also according to whether the device operates using an applied voltage, also referred to as a bias voltage or a bias voltage. Photoconductor cells do not have rectifying junctions and typically operate using a bias voltage. The PV device has at least one rectifying junction and operates without a bias voltage. The photodetector has at least one rectifying junction and is typically, but not always, operated using a bias voltage. Photovoltaic cells typically provide power to circuits, devices or equipment. The photodetector or photoconductor cell provides a signal or current to control or output information from the detection circuit, but does not provide power to the circuit, device or apparatus.

Photosensitive optoelectronic devices have traditionally been constructed from a variety of inorganic semiconductors, such as crystalline, polycrystalline and amorphous silicon, gallium arsenide, cadmium telluride, and the like. As used herein, the term "semiconductor" refers to a material that is capable of conducting electricity when charge carriers are induced by thermal or electromagnetic excitation. The term "photoconductive" generally refers to the process by which electromagnetic radiation energy is absorbed and converted to excitation energy of charge carriers so that the carriers can conduct, e.g., transport, charges in a material. The term "photoconductor" or "photoconductive material" is used herein to refer to semiconductor materials that are selected for their property of absorbing electromagnetic radiation to generate charge carriers.

The properties of PV devices can be characterized by their efficiency in converting incident solar energy into useful electrical energy. Devices utilizing crystalline or amorphous silicon dominate commercial applications, and some of these have achieved efficiencies of 23% or greater. However, crystal-based devices, particularly large surface area devices, are difficult and expensive to produce due to problems inherent in producing large crystals without significant efficiency-reducing defects. On the other hand, high efficiency amorphous silicon devices still suffer from stability problems. The stable conversion efficiency of currently commercially available amorphous silicon cells is between 4 and 8%. More recent attempts have focused on the use of organic photovoltaic cells to achieve acceptable photovoltaic conversion efficiencies at economical production costs.

The PV device may be optimized to operate under standard illumination conditions (i.e., standard test conditions, which are 1000W/m)²AM1.5 spectral illumination) for maximizing the product of photocurrent times photovoltage. The efficiency of the electrical energy conversion of such a cell under standard illumination conditions depends on the following three parameters: (1) current at zero bias, i.e. short-circuit current I_SCIn amperes; (2) photovoltage at open circuit condition, i.e. open circuit voltage V_OCIn volts; and (3) a fill factor ff.

The PV device, when connected to a load and illuminated with light, produces a photo-generated current. When illuminated under an infinite load, a PV device generates its maximum possible voltage, i.e., the open circuit voltage or V_OC. When the electrical contact thereof is shortWhen illuminated under the condition of a short circuit, the PV device generates its maximum possible current, i.e. short circuit current or I_SC. When actually used to generate power, the PV device is connected to a finite resistive load and the power output is given by the product of current and voltage I × V. The maximum total power generated by the PV device must not exceed the product I_SC×V_OC. When the load value is optimized for maximum power extraction, the current and voltage each have a value of I_maxAnd V_max。

The performance index of a PV device is the fill factor FF, which is defined as:

FF＝{I_maxV_max}/{I_SCV_OC} (1)

where FF is always less than 1, since in practical use I can never be obtained simultaneously_SCAnd V_OC. However, under optimum conditions, when FF is close to 1, the device has a lower series or internal resistance, thus providing a higher percentage of I to the load_SCAnd V_OCThe product of (a). When P is present_incPower efficiency of the device eta when incident power on the device_PCan be calculated from:

η_P＝FF*(I_SC*V_OC)/P_inc。

when electromagnetic radiation of suitable energy is incident on a semiconducting organic material, such as an Organic Molecular Crystal (OMC) material or a polymer, a photon may be absorbed to produce an excited molecular state. This is symbolized by S₀+hvΨS₀*. Where S is₀And S₀Denotes the ground and excited states of the molecule, respectively. This energy absorption is accompanied by an electron lifting from the ground state in the HOMO level, which may be a B-bond (B-bond), to the LUMO level, which may be a B-bond (B-bond), or equivalently, a hole lifting from the LUMO level to the HOMO level. In organic thin film photoconductors, it is generally believed that the molecular states generated are excitons, i.e., electron-hole pairs in a bound state that are transported as quasi-particles. Excitons may have appreciable lifetime before they combine in pairsBinding refers to the process by which the original electron and hole recombine with each other, as opposed to recombining with holes or electrons from other pairs. To generate a photocurrent, electron-hole pairs are separated, typically at the donor-acceptor interface between two different contacting organic thin films. If the charges are not separated, they can recombine in a pairwise recombination process, also known as a quenching process, in the form of radiation by emitting light of lower energy than the incident light, or in the form of non-radiation by generating heat. In photosensitive optoelectronic devices, either of these results is undesirable.

Inhomogeneities in the electric field or contacts may cause quenching of the exciton rather than dissociation at the donor-acceptor interface, resulting in no net contribution to current flow. It is therefore desirable to keep the photogenerated excitons away from the contacts. This has the effect of limiting the diffusion of excitons to regions near the junction so that the associated electric field has more opportunity to separate charge carriers released by exciton dissociation near the junction.

In order to generate an internal electric field that occupies a significant volume, it is common practice to juxtapose two layers of material having appropriately selected conductive properties, particularly in terms of the quantum energy state distribution of its molecules. The interface of these two materials is known as a photovoltaic heterojunction. In conventional semiconductor theory, the materials used to form PV heterojunctions are generally referred to as n-or p-type. Here n-type means that most of the carrier type is electrons. This can be viewed as a material having many electrons in relatively free energy states. p-type means that most of the carrier type is holes. Such materials have many holes in relatively free energy states. The type of background, i.e. the majority carrier concentration that is not photogenerated, depends mainly on unintentional doping by defects or impurities. Impurities and types and concentrations determine the value of the energy gap between the Highest Occupied Molecular Orbital (HOMO) level and the Lowest Unoccupied Molecular Orbital (LUMO) level, referred to as the Fermi energy (Fermi energy) or energy level in the HOMO-LUMO energy gap. Fermi energy describes the statistical occupancy of a quantum energy state of a molecule, expressed in terms of the energy value at which the probability of occupancy equals 1/2. The proximity of the fermi energy to the LUMO energy level indicates that the electron is the dominant carrier. The proximity of the fermi energy to the HOMO energy level indicates that holes are the dominant carriers. Hence, fermi energy is an important qualitative property of conventional semiconductors, and the prototype PV heterojunction is traditionally a p-n interface.

The term "rectifying" especially refers to an interface having asymmetric conductive properties, i.e. an interface supporting charge transport in preferably one direction. Rectification is generally associated with the built-in electric field generated at the heterojunction between appropriately selected materials.

As used herein, and as is generally understood by those skilled in the art, a first "highest occupied molecular orbital" (HOMO) or "lowest unoccupied molecular orbital" (LUMO) energy level is "greater than" or "higher than" a second HOMO or LUMO energy level if the first energy level is closer to the vacuum energy level than the second energy level. Because Ionization Potential (IP) is measured as negative energy relative to vacuum level, a higher HOMO level corresponds to an IP with a smaller absolute value (less negative IP). Likewise, a higher LUMO energy level corresponds to an Electron Affinity (EA) having a smaller absolute value (EA that is less negative). On a conventional energy level diagram, the vacuum level is at the top and the LUMO level of a material is higher than the HOMO level of the same material. The "higher" HOMO or LUMO energy level appears closer to the top of this energy level diagram than the "lower" HOMO or LUMO energy level.

In the case of organic materials, the terms "donor" and "acceptor" refer to the relative positions of the HOMO and LUMO energy levels of two organic materials that are in contact but different. This is in contrast to the use of these terms in the case of inorganic materials, where "donor" and "acceptor" may refer to the dopant types that may be used to create inorganic n-type and p-type layers, respectively. In the case of organic materials, a material is an acceptor if the LUMO level of the material in contact with another material is low. Otherwise, it is the donor. In the absence of an external bias, electrons at the donor-acceptor junction move into the acceptor material, and holes move into the donor material, energetically favorable.

A significant property of organic semiconductors is carrier mobility. Mobility measures the ease with which charge carriers can move through a conductive material in response to an electric field. In the case of organic photosensitive devices, the layer containing materials that tend to conduct by electrons due to high electron mobility may be referred to as an electron transport layer or ETL. A layer containing a material that tends to conduct by holes due to high hole mobility may be referred to as a hole transport layer or HTL. In one embodiment, the acceptor material is ETL and the donor material is HTL.

Conventional inorganic semiconductor PV cells utilize p-n junctions to establish an internal electric field. Early organic thin film cells, such as reported by Tang's appl. phys lett.48, 183(1986), contained heterojunctions similar to those used in conventional inorganic PV cells. However, it is now recognized that in addition to the establishment of the p-n type junctions, the energy level detuning of the heterojunction plays an important role.

Due to the fundamental nature of the photogeneration process in organic materials, energy level detuning at the organic D-a heterojunction is believed to be important for the operation of organic PV devices. Upon photoexcitation of the organic material, localized Frenkel or charge transfer excitons are generated. In order to perform electrical detection or generate an electrical current, the bound excitons must dissociate into their component electrons and holes. Such a process can be induced by a built-in electric field, but the electric field typically found in organic devices (F10)⁶V/cm) is low. The most efficient exciton dissociation in organic materials occurs at the donor-acceptor (D-a) interface. At such an interface, a donor material with a low ionization potential forms a heterojunction with an acceptor material with a high electron affinity. Depending on the energy level arrangement of the donor and acceptor materials, dissociation of the exciton at such an interface may become energetically favorable, producing a free electron polaron in the acceptor material and a free hole polaron in the donor material.

Organic PV cells have many potential advantages over conventional silicon-based devices. Organic PV cells are lightweight, economical in the use of materials, and can be deposited on low cost substrates such as flexible plastic foils. However, organic PV devices typically have relatively low power conversion efficiencies, on the order of 1% or less. This is believed to be due in part to the secondary nature of the intrinsic photoconductive process. That is, carrier generation requires the generation, diffusion, and ionization or collection of excitons. Each of these processes is accompanied by an efficiency η. Subscripts may be used as follows: p denotes power efficiency, EXT denotes external quantum efficiency, a denotes photon absorption exciton generation, ED denotes diffusion, CC denotes collection, and INT denotes internal quantum efficiency. Using this notation:

η_P～η_EXT＝η_A*η_ED*η_CC

η_EXT＝η_A*η_INT

diffusion length (L) of excitons_D)(LD～50) Typically much less than the light absorption length (-500)) A compromise is therefore required between using a thick and therefore high impedance cell with multiple or highly folded interfaces or a thin cell with low light absorption efficiency.

Typically, singlet excitons are formed when light is absorbed in an organic thin film and forms excitons. Singlet excitons may decay to triplet excitons through an intersystem crossing mechanism. Energy is lost in the process, which results in lower efficiency of the device. If energy losses are not to be incurred from intersystem crossing, it is desirable to use materials that generate triplet excitons, since triplet excitons generally have a longer lifetime and therefore a longer diffusion length than singlet excitons.

By using an organometallic material in the photoactive region, the device of the present invention can efficiently utilize triplet excitons. We have found that the singlet-triplet mixing may be so strong for organometallic compounds that absorption involves excitation from the singlet ground state directly to the triplet excited state, eliminating the losses associated with the transition from the singlet excited state to the triplet excited state. The longer lifetime and diffusion length of triplet excitons compared to singlet excitons may allow the use of thicker photoactive regions because triplet excitons may diffuse a longer distance to reach the donor-acceptor heterojunction without sacrificing device efficiency.

Organic material-based solar cells are promising candidates for widespread solar energy generation due to their potential for low-cost, large-area commercial production. More recently, stack structures containing two or more individual cells have shown improved device performance.

Organic tandem solar cell with two or more subcells electrically coupled in series having an open circuit voltage (V)_OC) V added to a single sub-cell_OCThe unique advantage of the sum of (a). Previously, the same small molecule organic materials have been used in front and rear cells.

In some cases, two different donor materials are used in each subcell to enable absorption of a wide range of photon energies in the solar emission spectrum. It has been demonstrated that the use of chlorine [ subphthalocyanine ]]A single cell battery in which boron (III) (SubPc) is used as a donor material and fullerene is used as an acceptor material can obtain a V as high as 0.98V_OC。

Summary of The Invention

Organic photovoltaic devices are disclosed that include two or more organic photoactive regions located between a first electrode and a second electrode, wherein each organic photoactive region includes a donor and an acceptor. In one embodiment, the organic photovoltaic device comprises at least one exciton blocking layer and at least one charge carrying or charge transfer layer between two or more photoactive regions.

In one embodiment, at least one of the at least two photoactive regions comprises a donor-acceptor heterojunction formed by a planar heterojunction, a bulk heterojunction, a mixed heterojunction, a hybrid-planar-mixed heterojunction, or a nanocrystalline heterojunction. For example, the heterojunction may comprise a mixture of two or more materials selected from: subphthalocyanine (SubPc), C₆₀、C₇₀Squaric acid, copper phthalocyanine (CuPc), tin phthalocyanine (SnPc), chloroaluminum phthalocyanine (ClAlPc), and Diindenoperylene (DIP).

Using a carefully designed laminate cell with layer thickness, material selection, film order and film crystallinity simulation and fabrication, a device was produced with device performance that could be improved by 11%. As shown herein, a tandem cell using SubPc as a donor in cells comprising various thicknesses, material selection, thin film order, and thin film crystallinity was produced.

In addition, SubPc and copper phthalocyanine (CuPc) have complementary absorption ranges of 500-600nm and 600-700nm, respectively. As shown herein, a tandem cell using SubPc and CuPc as donors in a tandem solar cell results in improved uniformity of spectral response throughout the visible region compared to a single subcell. Thus, when the layer thicknesses of SubPc and CuPc are optimal, the absorption peaks in the front and back cells will be located in different wavelength regions, which will balance the photocurrents in the two subcells.

Methods of making the disclosed devices and methods of using the same are also disclosed.

Drawings

FIG. 1: is a graph showing the absorption coefficients of various organic semiconductor materials.

FIG. 2: the following steps: extinction coefficient maps for certain active materials used in solar cells. The upper part: relationship of these active materials to am1.5g daylight spectrum.

FIG. 3: is expressed at 100mW/cm²And AM1.5G irradiated laminated organic laminateSolar cell pair constant J_SC(mA/cm²) An optimized contour map. The device structure is glass/1500ITO/xSubPc/xC₆₀/5Ag/ySubPc/yC₆₀/100BCP/800Al。

FIG. 4: is expressed at 100mW/cm²And AM1.5G light irradiation condition, laminated organic laminated solar cell pair constant J_SC(mA/cm²) An optimized contour map. The device structure is glass/1500ITO/xSubPc/xC₆₀/5Ag/yCuPc/yC₆₀/100BCP/800Ag。

FIG. 5: is a contour plot of normalized light field in the following model tandem cell: glass/1500ITO/50MoO₃/145SubPc/180C₆₀/50PTCBI/10Ag/25MoO₃/120CuPc/100C₆₀/80BCP/1kAnd Ag. The area enclosed by the circle represents the absorption zone of the material.

FIG. 6: is a contour plot of normalized light field in the following model tandem cell: glass/1500ITO/175CuPc/100C₆₀/50PTCBI/10Ag/25MoO₃/105SubPc/345C₆₀/80BCP/1kAnd Ag. The area enclosed by the circle represents the absorption zone of the material.

FIG. 7: is a graph of the change in the model normalized photocurrent when the normalized thickness of the photoactive layer in the stacked device was varied. The structure is glass/1500ITO/175CuPc/100C₆₀/50PTCBI/10Ag/25MoO₃/105SubPc/345C₆₀/80BCP/1kAg。

FIG. 8: is expressed at 100mW/cm²And a contour diagram in which the laminated organic tandem solar cell is optimized for constant power efficiency (%) under am1.5g illumination conditions. The device structure is glass/1500ITO/50SubPc/x A SubPc:C₆₀(nano)/400C₆₀/5Ag/100CuPc/yCuPc:C₆₀(nano)/200C₆₀/100BCP/800Ag。

FIG. 9: is of SubPc/C₆₀Calculated contour plots of efficiency of tandem solar cells of front and back subcells of a planar heterojunction as a function of exciton diffusion length and series resistance. Assume that the ideal coefficient n is equal to 2.

FIG. 10: is provided with nanocrystalline SubPc/C₆₀Front cell and nano-crystalline CuPc/C₆₀Calculated contour plots of the efficiency of the stacked device of the rear cell as a function of exciton diffusion length and series resistance variation. The ideal coefficient is assumed to be 2. The model structure is shown on the right.

FIG. 11: are the performance of the front and back cells and the un-optimized stacked device with the front cell containing the SubPc and the back cell containing the CuPc. For 1sun (100 mW/cm)²) Lower linear (upper left) and logarithmic (lower left) J-V curves are plotted along with experimental (upper right) and model (lower right) external quantum efficiencies. The inset shows the device structure.

FIG. 12: are the performance of the front and back cells and the un-optimized stacked device with the front cell containing SubPc and the back cell containing SQ. For 1sun (100 mW/cm)²) Lower linear (upper left) and logarithmic (lower left) J-V curves and experimental (upper right) external quantum efficiencies are plotted. Device junctionThe construct is shown in the lower right.

FIG. 13: device structure of stacked devices and J-V curves under am1.5g illumination. 100mW/cm²Corresponding to a 1sun intensity.

FIG. 14: device structure of front (left) and rear (right) cells.

FIG. 15: a graph showing a comparison between the laminated (square), front (circular) and rear (triangular) cells. Also shows the V of the front and rear cells_OCSum of (star).

FIG. 16: normalized EQE for the stacked (square), front (round) and rear (triangular) cells, respectively. The laminate cell showed both the peak of SubPc and the extended shoulder of CuPc.

FIG. 17: various figures of the following experimentally generated devices are shown: glass/1500ITO/50MoO₃/10NPD/130SuPc/170C₆₀/50PTCBI/8Ag/25MoO₃/75CuPc/230C₆₀/70BCP/1kAnd Ag. Clockwise from top left: device structure, logarithmic and linear J-V curves at different light intensities, and device performance plotted against incident light power.

FIG. 18: a graph showing a comparison of the J-V curves of the front, back and laminate cells of figure 17.

FIG. 19: model EQE for front and back cells in the following stack: glass/1500ITO/50MoO₃/10NPD/130SuPc/170C₆₀/50PTCBI/8Ag/25MoO₃/75CuPc/230C₆₀/70BCP/1kAg。

FIG. 20: comparison of EQE of front and rear cells alone of fig. 19.

Detailed Description

Representative embodiments may also include a transparent charge transport layer or charge recombination layer. As described herein, charge transport layers differ from acceptor and donor layers by the fact that charge transport layers are typically, but not necessarily, inorganic (typically metals) and they may be chosen to be non-photoconductive. The term "charge transport layer" is used herein to refer to a layer that is similar to an electrode but different in that the charge transport layer transports charge carriers from only one small portion of the optoelectronic device to an adjacent small portion. The term "charge recombination layer" is used herein to refer to a layer similar to an electrode but different in that the charge recombination layer allows recombination of electrons and holes between stacked photosensitive devices and may also enhance the internal optical field strength near one or more active layers. The electrically load carrying bonding layer may be comprised of translucent metal nanoclusters, nanoparticles, or nanorods as described in U.S. patent No.6,657,378, which is incorporated herein by reference in its entirety.

In one embodiment, at least one electrode comprises a transparent conductive oxide such as Indium Tin Oxide (ITO), Tin Oxide (TO), Gallium Indium Tin Oxide (GITO), Zinc Oxide (ZO), and Zinc Indium Tin Oxide (ZITO), or a transparent conductive polymer such as Polyaniline (PANI).

When the electrode is a cathode, it may comprise a metal substitute, a non-metallic material, or a metallic material, for example, one selected from Ag, Au, Ti, Sn, and Al.

In one embodiment, the charge transport layer or charge heavy-binding layer may comprise Al, Ag, Au, MoO₃、Li、LiF、Sn、Ti、WO₃Indium Tin Oxide (ITO), Tin Oxide (TO), Gallium Indium Tin Oxide (GITO), Zinc Oxide (ZO), or Zinc Indium Tin Oxide (ZITO). In another embodiment, the charge recombination layer may comprise metal nanoclusters, nanoparticles, or nanorods.

As donor materials that can be used in the present disclosure, non-limiting examples that can be mentioned are selected from subphthalocyanine (SubPc), copper phthalocyanine (CuPc), chloroaluminum phthalocyanine (ClAlPc), tin phthalocyanine (SnPc), pentacene, tetracene, Diindenoperylene (DIP), and squaric acid (SQ).

Non-limiting embodiments of squaraine compounds that can be used are selected from the group consisting of 2, 4-bis [4- (N, N-dipropylamino) -2, 6-dihydroxyphenyl, 2, 4-bis [4- (N, N-diisobutylamino) -2, 6-dihydroxyphenyl, and salts thereof.

In one embodiment, the donor material may be doped with a high mobility material, such as a material comprising pentacene or metal nanoparticles.

In one embodiment, each organic photoactive region described herein may comprise a donor that exhibits a complementary absorption range to the donor of at least one other organic photoactive region.

For the receptor materials that can be used in the present disclosure, non-limiting examples that may be mentioned are selected from C₆₀、C₇₀3, 4, 9, 10-perylenetetracarboxylic bis-benzimidazole (PTCBI), phenyl-C₆₁-butyric acid-methyl ester ([ 60)]PCBM), phenyl-C₇₁-butyric acid-methyl ester ([ 70)]PCBM), thienyl-C₆₁-butyric acid-methyl ester ([ 60)]ThCBM) and hexadecafluorophthalocyanine (F)₁₆CuPc)。

As materials which can be used as exciton blocking layer, non-limiting examples which may be mentioned are those selected from Bathocuproine (BCP), bathophenanthroline (BPhen), 3, 4, 9, 10-perylenetetracarboxylic bis-benzimidazole (PTCBI), 1, 3, 5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBi), tris (acetylacetonato) ruthenium (III) (Ru (acaca))₃) And aluminum (III) phenolate (Alq)₂ OPH)。

Non-limiting examples of material mixtures that can be used to form the heterojunction include:

subphthalocyanine (SubPc)/C₆₀；

Subphthalocyanine (SubPc)/C₇₀；

Squaric acid/C₆₀；

Copper phthalocyanine (CuPc)/C₆₀；

Copper phthalocyanine (CuPc)/tin phthalocyanine (SnPc)/C₆₀(ii) a Or

Diindenoperylene (DIP)/C₇₀；

Aluminum chloro phthalocyanine (AlClPc)/C₆₀(ii) a And

aluminum chloro phthalocyanine (AlClPc)/C₇₀。

In one embodiment, the photoactive layers described herein further comprise a buffer material, e.g., WO₃、V₂O₅、MoO₃And other oxides.

In the fabrication of the organic photovoltaic devices described herein, one or more organic layers may be deposited by vacuum thermal evaporation, organic vapor jet printing, or organic vapor deposition. Alternatively, the organic layer may be deposited using solution processing methods such as doctor blading, spin coating or inkjet printing.

The thickness of the organic layers used in the organic photovoltaic devices described herein can be in the range of 25-1200 aIn the range of, for example, 50 to 950Or even 60-400

In one embodiment, the organic layer is crystalline and may be crystalline over a large area, for example from 100nm to 1000nm, or even in the range from 10nm to 1 cm.

The organic photovoltaic devices described herein may exhibit open circuit voltages (V) ranging up to 2.2V, e.g., 1.57V_oc) And a power efficiency (η) higher than 2%, even higher than 10%_p). In one embodiment, the organic photovoltaic devices described herein may exhibit a power efficiency of greater than 11%.

In one embodiment, the organic photovoltaic devices described herein can comprise three or more organic photoactive regions, each comprising a donor and an acceptor. In one embodiment, the device further comprises at least one exciton blocking layer, charge recombination layer, or charge transport layer, and optionally a buffer layer.

In another embodiment, the organic photovoltaic devices described herein comprise two or more organic photoactive regions located between a first electrode and a second electrode,

wherein each of the organic photoactive regions comprises:

a donor comprising a material selected from the group consisting of: subphthalocyanine (SubPc), copper phthalocyanine (CuPc), chloroaluminum phthalocyanine (ClAlPc), tin phthalocyanine (SnPc), pentacene, tetracene, Diindenoperylene (DIP), squaric acid (SQ), zinc phthalocyanine (ZnPc), and lead phthalocyanine (PbPc);

a receptor comprising the following materials: is selected from C₆₀、C₇₀3, 4, 9, 10-perylenetetracarboxylic bis-benzimidazole (PTCBI), phenyl-C₆₁-butyric acid-methyl ester ([ 60)]PCBM), phenyl-C₇₁-butyric acid-methyl ester ([ 70)]PCBM), thienyl-C₆₁-butyric acid-methyl ester ([ 60)]ThCBM) and hexadecafluorophthalocyanine (F)₁₆CuPc)；

An exciton blocking layer comprising a material selected from the group consisting of: WO₃、MoO₃Bathocuproine (BCP), bathophenanthroline (BPhen), 3, 4, 9, 10-perylenetetracarboxybis-benzimidazole (PTCBI), 1, 3, 5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBi), ruthenium (III) (Ru (acaca))₃)；

An electrically load-bonding or charge-transfer layer comprising a material selected from Al, Ag, Au, MoO₃And WO₃The material of (a); and optionally MoO₃The buffer layer of (2);

wherein at least one electrode is an anode comprising Indium Tin Oxide (ITO) and at least one electrode is a cathode comprising a material selected from Ag, Au and Al.

In this embodiment, similar to the other embodiments, the at least one photoactive region may comprise a donor-acceptor heterojunction formed by a planar heterojunction, a bulk heterojunction, a mixed heterojunction, a hybrid-planar-mixed heterojunction, or a nanocrystalline bulk heterojunction. As stated previously, the heterojunction comprises a mixture of two or more materials selected from: subphthalocyanine (SubPc), C₆₀、C₇₀Squaric acid, copper phthalocyanine (CuPc), tin phthalocyanine (SnPc), Diindenoperylene (DIP), and aluminum phthalocyanine chloride (AlClPc).

subphthalocyanine (SubPc)/C₆₀；

Subphthalocyanine (SubPc)/C₇₀；

Squaric acid/C₆₀；

Copper phthalocyanine (CuPc)/C₆₀；

Copper phthalocyanine (CuPc)/tin phthalocyanine (SnPc)/C₆₀；

Diindenoperylene (DIP)/C₇₀；

Aluminum chloro phthalocyanine (AlClPc)/C₆₀；

Aluminum chloro phthalocyanine (AlClPc)/C₇₀(ii) a Or

Copper phthalocyanine (CuPc)/aluminum phthalocyanine chloride (AlClPc)/C₆₀。

The invention also discloses a method for producing an organic photovoltaic device, the method comprising:

depositing a first electrode on a substrate;

depositing a first photoactive region on the first electrode;

depositing a first charge recombination or charge transport layer over the first photoactive region;

depositing a second photoactive region on the first charge recombination or charge transfer layer; and

depositing a second electrode on the second photoactive region;

wherein the first organic photoactive region comprises a first donor and a first acceptor,

wherein the second organic photoactive region comprises a second donor and a second acceptor,

wherein an exciton blocking layer is deposited on at least one photoactive region, and

wherein an electrically charged binding layer, charge transfer layer or electrode is deposited between each photoactive region.

Furthermore, the present invention discloses a method for generating and/or measuring an electrical or electrical signal, the method comprising providing light to an organic photovoltaic device as described herein.

Using the optimization method described above, the inventors have found that it is possible to manufacture many different types of tandem solar cells. One non-limiting structure is as follows: glass/1500ITO/x₁Donor 1/x₂Receptor 1/x₃Exciton blocking layer/x₄Electrically charge-binding or charge-transfer layers/y₁Donor 2/y₂Receptor 2/y₃Exciton blocking layer/y₄A metal cathode. Another non-limiting structure is as follows: glass/1500ITO/x₁Buffer 1/X₁Donor 1/x₂Receptor 1/x₃Exciton blocking layer/x₄Electrically charge-binding or charge-transfer layers/y₁Buffer 2/y₁Donor 2/y₂Receptor 2/y₃Exciton blocking layer/y₄A metal cathode.

The donor material includes SubPc, CuPc, and chloroaluminum phthalocyanine (ClAlPc)) Tin phthalocyanine (SnPc), pentacene, tetracene, Diindenoperylene (DIP), squaric acid (SQ), and the like. The acceptor material comprises the fullerene family (C)₆₀、C₇₀、C₈₀、C₈₄Etc.), 3, 4, 9, 10-perylenetetracarboxylic bis-benzimidazole (PTCBI), hexadecafluorophthalocyanine (F)₁₆CuPc), and the like. Exciton blocking layers include Bathocuproine (BCP), bathophenanthroline (BPhen), PTCBI, 1, 3, 5-tris (N-phenylbenzimidazol-2-ylbenzene (TPBi), and the like.

The charge-recombination or charge-transfer layer between the cells may comprise Al, Ag, Au, MoO₃、WO₃Including nanoclusters thereof, etc., while the cathode may comprise Al, Ag, Au, or other metals.

The following U.S. patents are incorporated herein by reference for their teachings of materials such as donors, acceptors, blocking layers, charge recombination layers, charge transport layers, other layers, etc., that may be used in the organic stacked devices of the present invention: 6,657,378, 6,278,055 and 7,326,955.

The buffer may be selected from metal oxides such as WO₃、V₂O₅、MoO₃Etc. or organic materials such as NPD, Alq₃And the like.

Examples of possible planar heterojunction stack structures are shown in table 1. By repeating the sequence of donor/acceptor/exciton blocking layer/charge recombination layer or charge transfer layer, stacked devices of more than two sub-cells are also possible.

Table 1. example structure of a planar heterojunction tandem solar cell.

Donor

Receptors

Barrier

Layer(s)

Donor

Receptors

Barrier

Layer(s)

CuPc

C₆₀

PTCBI

Ag/MoO₃

SubPc

C₇₀

BCP

Ag

CuPc

C₇₀

PTCBI

Ag/WO₃

SubPc

C₆₀

PTCBI

Al

SubPc

C₆₀

PTCBI

Ag

CuPc

C₆₀

BCP

Ag

SubPc

C₇₀

PTCBI

Ag

CuPc

C₆₀

BPhen

Au

SubPc

C₆₀

BCP

Ag

DIP

C₆₀

BCP

Ag

SQ

C₆₀

BCP

Ag

SubPc

C₇₀

PTCBI

Al

ClAlPc

C₆₀

BCP

WO₃

SubPc

C70

BCP

Al

CuPc

F₁₆CuPc

BPhen

MoO₃

SubPc

C₇₀

TPBi

Al

Layer being a charge transfer layer or charge recombination layer

An example of a device containing three planar heterojunction subcells is shown in table 2.

Table 2. example structure of a planar heterojunction solar cell with three subcells.

Donor

A

B

L

Donor

A

B

L

Donor

A

B

C

SubPc

C₆₀

BCP

Ag

CuPc

F₁₆CuPc

BCP

Ag

SQ

C₇₀

BCP

Al

SubPc

C₇₀

BPhen

MoO₃

DIP

C₆₀

PTCBI

WO₃

ClAlPc

C₆₀

BCP

Ag

DIP

C₆₀

PTCBI

Ag

SubPc

C₇₀

BCP

Ag

CuPc

C₆₀

BCP

Ag

A ═ receptor layer

B ═ barrier layer

C ═ cathode

L ═ charge transport or charge recombination layers

As shown in fig. 1, the diversity of the absorption coefficients of organic semiconductor materials offers numerous possibilities for complementary absorption in the daylight spectral range.

Various thin film morphologies may also be utilized within each subcell, including planar heterojunctions, Bulk Heterojunctions (BHJ), Mixed Heterojunctions (MHJ), and nanocrystalline heterojunctions (ncBHJ). Examples of planar heterojunction devices are shown in tables 1-3.

TABLE 3 exemplary Structure of planar heterojunction tandem solar cells incorporating mixed layers

A ═ receptor layer

B ═ barrier layer

C ═ cathode

L ═ charge transport or charge recombination layers

Devices may be fabricated by Vacuum Thermal Evaporation (VTE) and/or organic vapor deposition (OVPD). The incorporation of high mobility materials, such as pentacene, into the donor material may be another way to improve device performance.

Engineering of thin film crystallinity is also required to optimize device performance. It has been proposed that as the crystal size increases, the exciton diffusion length (L) increases_D) Increase, and series resistance (R)_S) And decreases. This will allow the active layer thickness to be increased proportionately, resulting in more exciton dissociation and J_SCAnd (4) increasing. Growth by OVPD has been shown to provide more control over film crystallinity in some cases.

Due to the tremendous parametric design space (order of layers, layer materials, layer thicknesses, number of layers, etc.), certain parameters must be set before optical simulations can be performed to optimize the device. The first step is to select a photoactive material that has a high V and a desired absorption wavelength that has been demonstrated for a single device_OCTo select. There is a necessary tradeoff in this choice because materials that absorb longer wavelengths typically have smaller optical bandgaps, and thus produce materials with lower V_OCThe device of (1). Next, the upper and lower ranges of the set layer thickness must be considered. Too thin a layer will be discontinuous, creating leaky or parallel segments, while too thick a layer can increase the resistance of the device and inhibit carrier transport. Once these parameters are selected, the thickness can be optimized using a light field model.

The stack combination of an organic solar cell with two sub-cells electrically coupled in series can be investigated from an optical point of view and then be combined withThe electrical model of charge generation and transport in solar cells is integrated. For solar cells, there are three characteristics that affect the power conversion efficiency (η)_p): short-circuit current (J)_SC)、V_OCAnd a Fill Factor (FF). J. the design is a square_SCMainly as a function of two competing parameters: exciton diffusion length (L)_D) And an absorption coefficient (α). In order to generate current by exciton dissociation at the heterojunction interface, the film thickness is generally limited to 1-2 times the LD. L in organic Material_DIs typically on the order of tens or hundreds of angstroms; the thickness (given by 1/a) required to absorb all photons is typically on the order of a few thousand angstroms.

In series stacked solar cells, the J produced by each subcell under operating light intensity_SCGenerally equal to prevent the build-up of photo-generated charge. The photocurrent can be balanced by varying the thickness and order of the individual layers of the solar cell in the stack and taking into account the optical interference effects in the layers. V_OCTypically the sum of the voltages of the sub-cells. These parameters and L measured by experiment_DAnd the value of alpha is introduced into a model using a well-developed transfer matrix method to determine the optimal device structure. Fig. 2 shows the measured optical constants of the active layer and their relationship to the solar spectrum in some cases.

Models have been established for several exemplary planar heterojunction stacked devices. For a stacked cell using a SubPc donor material in both the front cell and the back cell, the prototype layer structure is as follows: glass/1500ITO/x₁SubPc/x₂C₆₀/5Ag/y₁SubPc/y₂C₆₀/100BCP/800And Al. An exemplary laminate battery has the following layer structure: glass/1500ITO/105SubPc/105C₆₀/5Ag/130SubPc/130C₆₀/100BCP/800Al, wherein J is obtained_SCIs 3.3mA/cm². As shown in FIG. 3, the optimized efficiency is η_p＝3.2％。

Terms such as X are used herein₁And refers to the location and layers in each cell. For example at "X₁"where x denotes the front cell and the subscript is the layer in the cell, where 1 denotes the first layer. Likewise, y₂Representing the rear cell and the second layer.

It may also be a battery with a SubPc donor material in the front cell and with CuPc/C₆₀The rear cell was modeled as a tandem cell that increased the visible spectrum absorption. As shown in fig. 4, an exemplary stacked cell structure is as follows: glass/1500ITO/120SubPc/120C₆₀/5Ag/110CuPc/110C₆₀/100BCP/800Ag, wherein J is optimized_SCIs 4.2mA/cm²Efficiency η_pIs 3.3%.

A third modeled stack cell had a SubPc donor material in the front cell and a CuPc back cell, with an exemplary structure as follows: glass/1500ITO/50MoO₃/145SubPc/180C₆₀/50PTCBI/10Ag/25MoO₃/120CuPc/100C₆₀/80BCP/1kAg, in which J is obtained_SCIs 3.8mA/cm². Suppose FF is 0.60 and V_OCIs 1.43V, optimized eta_pIs 3.3%. Fig. 5 shows that the absorption region (enclosed by circles) of each material is not at the maximum optical field of those wavelengths.

Finally, a model was established for a laminate cell using CuPc in the front cell and SubPc in the rear cell. An exemplary laminate cell is as follows: glass/1500ITO/175CuPc/100C₆₀/50PTCBI/10Ag/25MoO₃/105SubPc/345C₆₀/80BCP/1kAg, in which J is obtained_SCIs 5.1mA/cm². Suppose FF is 0.60 and V_OCIs 1.43V, optimized eta_pIs 4.4%. FIG. 6 shows a model light field in the structure; the absorption region is well matched to the optical field.

It is important to note that the simple stacking of two active solar cells does not necessarily result in an active tandem cell. Due to the complex optical interference and absorption bands of each layer, an optical model must be built in order to obtain high efficiency. Using and optimizing CuPc/C₆₀And SubPc/C₆₀An exemplary non-optimized laminate cell of similar structural design for individual cells is as follows: glass/1500ITO/20NPD/120SubPc/250C₆₀/50PTCBI/10Ag/20MoO₃/150CuPc/400C₆₀/100BCP/1kAl, wherein J is obtained_SCIs 1.3mA/cm². Suppose FF is 0.60 and V_OCIs 1.43V,. eta_pIs 1.3%. FIG. 7 shows normalized J as a result of optimizing the normalized thickness variation of the active layer in the device_SCThe result of the changed model. It can be seen that for large changes in thickness, the device performance drops significantly, while for small changes (within experimental error) there is only a small drop.

A comparison of the performance of these devices is summarized in table 4.

Table 4 device performance of the following modeled devices: glass/1500ITO/175CuPc/100C₆₀/50PTCBI/10Ag/25MoO₃/105SubPc/345C₆₀/80BCP/1kAg。

Previously, nanocrystalline heterojunction (ncBHJ) CuPc: C composed of ordered, interdigitated interfaces has been grown by organic vapor deposition₆₀A solar cell is provided. Due to efficient exciton dissociation and low series resistance, these devices show significantly improved efficiency compared to otherwise identical planar heterojunction solar cells. By combining other nanocrystalline materials, it may be possible to model and fabricate very efficient solar cells. As an example, ncBHJ SubPc: C has been established₆₀And CuPc: C₆₀The model acts as two subcells in a stacked configuration. Thus, the ncBHJ cell was powered back using SubPc in the preceding cellA stack cell assembly using CuPc in the cell, an exemplary stack cell structure is as follows: glass/1500ITO/50SubPc/950SubPc:C₆₀ncBHJ/400C₆₀/5Ag/100CuPc/175CuPc:C₆₀ ncBHJ/200C₆₀/100BCP/800Ag, the maximum efficiency of 6.6% as shown in fig. 8 was obtained.

It is also possible, and sometimes desirable, to fabricate devices with high crystallinity. The performance of organic electronic devices is relatively low compared to inorganic devices because of the low diffusion length and high resistance caused by the highly disordered thin films. Without being bound by any theory, it is expected that these limitations will be reduced in more ordered films. FIG. 9 shows the efficiency of a SubPc/SubPc tandem cell similar to that of FIG. 3 versus L_DAnd R_SA contour diagram of (a).

An idealized efficiency of 6.8% may be possible, which is more than twice that of the amorphous structure. A similar plot for the SubPc: CuPc ncBHJ cell is shown in fig. 10, with an increase of more than 11% being obtained for the following structure: glass/1500ITO/120SubPc/1500SubPc:C₆₀ ncBHJ/700C₆₀/5Ag/50CuPc/468CuPc:C₆₀ncBHJ/158C₆₀/80BCP/1kAnd Ag. Highly ordered films have previously been demonstrated using OVPD or structural simulations.

Examples

Exemplary device

With further reference to FIG. 10, for bottom powerFor the cell (which is close to the ITO anode side), SubPc/C is used₆₀Nanocrystalline cell with 120 deposited as a continuous wetting layerSubPc, then the thickness is 1500Nano crystal C of₆₀the/SubPc multilayer is deposited on top of the original SubPc wetting layer. Next, apply 700To complete the front cell. For the intermediate layer, Ag is used as a recombination center to balance photocurrents generated in the front cell and the rear cell.

The top cell (which is near the Ag cathode side) is a CuPc/C60 nanocrystal cell with 50 deposited thereonCuPc as a continuous wetting layer. On top of the original CuPc wetting layer is a layer 468 in thicknessNano crystal C of₆₀a/CuPc multilayer, then 158C60 donor layers and 80A BCP barrier layer. Metallic Ag serves as the cathode.

Other devices

The initial stack of stacked devices was fabricated by vacuum thermal evaporation. At less than 5X 10^-7Base pressure of Torr, the film is heated to 1At a rate of deposition in a pre-coatWith indium-doped tin oxide (ITO) (Prazitions Glas)&Optik GmbH, germany). At 0.5A charge recombination layer consisting of metal nanoclusters was deposited and a metal cathode was deposited through a circular shadow mask with a diameter of 1 mm. I-V and power efficiency were measured using an Oriel 150W solar simulator with an AM1.5G filter, and External Quantum Efficiency (EQE) was measured using a monochromatic beam cut to 400Hz from a Xe light source. The light intensity was measured using a solar cell calibrated by the National Renewable Energy Laboratory (National Renewable Energy Laboratory) and the photocurrent spectrum was measured using a lock-in amplifier.

A first device provided is an unoptimized laminate cell having the following structure: glass/1500ITO/20NPD/120SubPc/250C₆₀/50PTCBI/10Ag/20MoO₃/150CuPc/400C₆₀/100BCP/1kAl, wherein J is measured_SCIs 2.1mA/cm²FF of 0.45 and V_OC1.24V, η produced_p1.16 +/-0.02 percent. The device characteristics are shown in fig. 11. Table 5 compares the performance of the front, back and laminate cells and shows that for an unoptimized laminate cell, the resulting device has a significantly lower J than the individual cells_SC。

Table 5 device performance of the devices grown experimentally: glass/1500ITO/20NPD/120SubPc/250C₆₀/50PTCBI/10Ag/20MoO₃/150CuPc/400C₆₀/100BCP/1kAl。

Device with a metal layer	η_p(％)	V_OC(V)	FF	JSC(mA/cm²)	Model J_SC
						Rear battery only	0.54±0.01	0.36	0.54	2.8	6.0
Front battery only	1.39±0.01	0.96	0.38	3.9	4.4
						Laminated battery	1.16±0.02	1.24	0.45	2.1	1.3

A second device provided is an unoptimized laminate cell having the following structure: glass/1500ITO/135SubPc/250C₆₀/50PTCBI/5Ag/50NPD/80SQ/400C₆₀/100BCP/1kAg, wherein J is measured_SCIs 2.1mA/cm²FF of 0.44, V_OCIs 1.11V, eta produced_p1.00 +/-0.02%. The device characteristics are shown in fig. 12. Table 6 compares the performance of the front, back and laminate cells and shows that for an unoptimized laminate cell, the resulting device has a significantly lower J than the individual cells_SC。

Table 6 device performance of the devices grown experimentally: glass/1500ITO/135SubPc/250C₆₀/50PTCBI/5Ag/50NPD/80SQ/400C₆₀/100BCP/1kAg。

Device with a metal layer	η_p(％)	V_OC(V)	FF	J_SC(mA/cm²)
					Rear battery only	0.71±0.01	0.66	0.29	3.7
Front battery only	2.12±0.09	0.93	0.53	4.3
					Laminated battery	1.00±0.02	1.11	0.44	2.1

A third device provided is an optimized laminate cell with a CuPc front cell and a CuPc rear cell. Fig. 13 shows the structure of a stacked device: glass/150 nm ITO/120SubPc/30SubPc:C₆₀ 1:1/200C₆₀/50PTCBI/5Ag nanocluster/200CuPc/300C₆₀/80BCP/1kAg, and J-V curves at varying light intensities.

Fig. 14 shows the structure of the front and rear cells for comparison. V of a laminate cell compared to a single sub-cell_OCShows a close to the sum of the individual cells (1.47V vs. CuPc/C at 1sun₆₀0.45V and SubPc/C of₆₀1.08V) as shown in fig. 15.

The normalized EQE data in fig. 16 shows that both CuPc and SubPc contribute to photocurrent, with the peak of SubPc between 500 and 600nm and the broad shoulder of CuPc outside 650nm being present.

The fourth device is an optimized stacked cell with a SubPc front cell and a CuPc rear cell. Fig. 17 shows the structure of a stacked device: glass/1500ITO/25MoO₃/10NPD/130SuPc/170C₆₀/50PTCBI/8Ag/25MoO₃/75CuPc/230C₆₀/70BCP/1kAg, and J-V curves at various light intensities.

Figure 18 shows the J-V characteristics of the front and rear cells for comparison. V of a laminate cell compared to a single sub-cell_OCShows a close to the sum of the individual cells (1.57V vs. CuPc/C at 1sun₆₀0.38V and SubPc/C of₆₀1.12V).

The model EQE for this structure in FIG. 19 shows, CuPc/C₆₀In the rear batteryIs SubPc/C₆₀The front cell is filled. Fig. 20 compares the experimental and model EQE for the front and rear cells alone. Although the performance of these devices was below model values (probably due to contamination during growth), these data show that the performance of well-designed stacked devices can be as good as the sum of the individual cells. The device properties are shown in table 7.

Table 7 device performance of the following experimentally grown devices: glass/1500ITO/25MoO₃/10NPD/130SuPc/170C₆₀/50PTCBI/8Ag/25MoO₃/75CuPc/230C₆₀/70BCP/1kA。

Device with a metal layer	η_p(％)	V_OC(V)	FF	J_SC(mA/cm²)	Model J_SC
						Rear battery only	0.66±0.04	0.38	0.59	2.9	5.7
Front battery only	1.67±0.01	1.12	0.55	2.7	3.7
						Laminated battery	2.30±0.03	1.57	0.52	2.8	3.2

Unless otherwise indicated, all numbers expressing quantities of ingredients, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term "about". Accordingly, unless indicated to the contrary, the numerical parameters set forth in the specification and claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention.

Other embodiments of the invention will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

Claims

1. An organic photovoltaic device comprising two or more organic photoactive regions between a first electrode and a second electrode,

wherein each of the organic photoactive regions comprises a donor and an acceptor, and wherein the organic photovoltaic device comprises at least one exciton blocking layer and at least one electrical charge loading binding or charge transfer layer between two or more photoactive regions.

2. The organic photovoltaic device of claim 1, wherein at least one electrode comprises a transparent conductive oxide or a transparent conductive polymer.

3. The organic photovoltaic device according TO claim 2, wherein the conductive oxide is selected from the group consisting of Indium Tin Oxide (ITO), Tin Oxide (TO), Gallium Indium Tin Oxide (GITO), Zinc Oxide (ZO), and Zinc Indium Tin Oxide (ZITO), and the transparent conductive polymer comprises Polyaniline (PANI).

4. The organic photovoltaic device of claim 1, wherein at least one of said electrodes is a cathode comprising a metal substitute, a non-metallic material, or a metallic material selected from Ag, Au, Ti, Sn, and Al.

5. The organic photovoltaic device of claim 1, wherein the electrical load bonding layer or the charge transport layer comprises Al, Ag, Au, MoO₃、Li、LiF、Sn、Ti、WO₃Indium Tin Oxide (ITO), Tin Oxide (TO), Gallium Indium Tin Oxide (GITO), Zinc Oxide (ZO), or Zinc Indium Tin Oxide (ZITO).

6. The organic photovoltaic device of claim 5, wherein the electrical charge binding or charge transport layer comprises metal nanoclusters, nanoparticles, or nanorods.

7. The organic photovoltaic device of claim 1, wherein the donor is selected from subphthalocyanine (SubPc), copper phthalocyanine (CuPc), chloroaluminum phthalocyanine (ClAlPc), tin phthalocyanine (SnPc), pentacene, tetracene, Diindenoperylene (DIP), and Squaraine (SQ).

8. The organic photovoltaic device according to claim 7, wherein the squaraine compound is selected from the group consisting of 2, 4-bis [4- (N, N-dipropylamino) -2, 6-dihydroxyphenyl, 2, 4-bis [4- (N, N-diisobutylamino) -2, 6-dihydroxyphenyl, and salts thereof.

9. The organic photovoltaic device of claim 1, wherein each of said organic photoactive regions comprises a donor exhibiting a complementary absorption range to the donor of at least one other organic photoactive region.

10. The organic photovoltaic device of claim 1, wherein the acceptor is selected from C₆₀、C₇₀3, 4, 9, 10-perylenetetracarboxylic bis-benzimidazole (PTCBI), phenyl-C₆₁-butyric acid-methyl ester ([ 60)]PCBM), phenyl-C₇₁-butyric acid-methyl ester ([ 70)]PCBM), thienyl-C₆₁-butyric acid-methyl ester ([ 60)]ThCBM) and hexadecafluorophthalocyanine (F)₁₆CuPc)。

11. The organic photovoltaic device of claim 1, wherein the exciton blocking layer is selected from Bathocuproine (BCP), bathophenanthroline (BPhen), 3, 4, 9, 10-perylenetetracarboxybis-benzimidazole (PTCBI), 1, 3, 5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBi), tris (acetylacetonate) ruthenium (III) (Ru (acaca)₃) And aluminum (III) phenolate (Alq)₂OPH)。

12. The organic photovoltaic device of claim 1, wherein at least one of the at least two photoactive regions comprises a donor-acceptor heterojunction formed from a planar heterojunction, a bulk heterojunction, a mixed heterojunction, a hybrid-planar-mixed heterojunction, or a nanocrystalline bulk heterojunction.

13. The organic photovoltaic device of claim 12, wherein the heterojunction comprises a mixture of two or more materials selected from the group consisting of: subphthalocyanine (SubPc), C₆₀、C₇₀Squaric acid, copper phthalocyanine (CuPc), tin phthalocyanine (SnPc), and Diindenoperylene (DIP).

14. The organic photovoltaic device of claim 13, wherein the mixture comprises:

subphthalocyanine (SubPc)/C₆₀；

Subphthalocyanine (SubPc)/C₇₀；

Squaric acid/C₆₀；

Copper phthalocyanine (CuPc)/C₆₀；

Copper phthalocyanine (CuPc)/tin phthalocyanine (SnPc)/C₆₀(ii) a Or

Diindenoperylene (DIP)/C₇₀；

Aluminum chloro phthalocyanine (AlClPc)/C₆₀(ii) a And

aluminum chloro phthalocyanine (AlClPc)/C₇₀。

15. The organic photovoltaic device of claim 1, wherein at least one photoactive layer further comprises a buffering agent.

16. The organic photovoltaic device of claim 15, wherein the buffer is MoO₃。

17. The organic photovoltaic device of claim 1, wherein at least one organic layer is deposited by vacuum thermal evaporation, organic vapor jet printing, or organic vapor deposition.

18. The organic photovoltaic device of claim 1, wherein at least one organic layer is deposited by a solution processing method selected from the group consisting of doctor blading, spin coating, and ink jet printing.

19. The organic photovoltaic device of claim 1, wherein the donor is doped with a high mobility material.

20. The organic photovoltaic device according to claim 19, wherein the high mobility material comprises pentacene.

21. The organic photovoltaic device of claim 17, wherein the organic layer has a thickness in the range of 25 a to 1200 aWithin the range.

22. The organic photovoltaic device of claim 1, wherein at least one organic layer is crystalline.

23. The organic photovoltaic device of claim 22, wherein the organic layer is crystalline in the range of 10nm to 1 cm.

24. The organic photovoltaic device of claim 1, wherein the device exhibits an open circuit voltage (V) ranging up to 2.2V_oc)。

25. The organic photovoltaic device of claim 1, wherein the device exhibits a power efficiency (η) greater than 2%_p)。

26. The organic photovoltaic device of claim 25, wherein the model device exhibits a power efficiency (η) greater than 10%_p)。

27. The organic photovoltaic device of claim 1, wherein the device comprises three or more organic photoactive regions, each comprising a donor and an acceptor, the device further comprising at least one exciton blocking layer, charge recombination layer, or charge transfer layer, and optionally a buffer layer.

28. A method of producing an organic photovoltaic device, the method comprising:

depositing a first electrode on a substrate;

depositing a first photoactive region on the first electrode;

depositing a second electrode on the second photoactive region;

29. A method of generating and/or measuring electricity or an electrical signal, the method comprising providing light to the organic photovoltaic device of claim 1.

30. An organic photovoltaic device comprising two or more organic photoactive regions between a first electrode and a second electrode,

wherein each of the organic photoactive regions comprises:

a receptor comprising a material selected from the group consisting of: c₆₀、C₇₀3, 4, 9, 10-perylenetetracarboxylic bis-benzimidazole (PTCBI), phenyl-C₆₁-butyric acid-methyl ester ([ 60)]PCBM), phenyl-C₇₁-butyric acid-methyl ester ([ 70)]PCBM), thienyl-C₆₁-butyric acid-methyl ester ([ 60)]ThCBM) and hexadecafluorophthalocyanine (F)₁₆CuPc)；

An exciton blocking layer comprising a material selected from the group consisting of: WO₃、MoO₃Bathocuproine (BCP), bathophenanthroline (BPhen), 3, 4, 9, 10-perylenetetracarboxylic bis-benzimidazole (PTCBI) and 1, 3, 5-tris (N-phenylbenzimidazol-2-yl) benzene (TPBi);

wherein at least one of said electrodes is an anode comprising Indium Tin Oxide (ITO) and at least one of said electrodes is a cathode comprising a material selected from the group consisting of Ag, Au and Al.