WO2007070395A2 - Dispositifs photovoltaiques tandem bases sur un nouveau copolymere sequence - Google Patents

Dispositifs photovoltaiques tandem bases sur un nouveau copolymere sequence Download PDF

Info

Publication number
WO2007070395A2
WO2007070395A2 PCT/US2006/046951 US2006046951W WO2007070395A2 WO 2007070395 A2 WO2007070395 A2 WO 2007070395A2 US 2006046951 W US2006046951 W US 2006046951W WO 2007070395 A2 WO2007070395 A2 WO 2007070395A2
Authority
WO
WIPO (PCT)
Prior art keywords
sub
block copolymer
conjugated
cell
donor
Prior art date
Application number
PCT/US2006/046951
Other languages
English (en)
Other versions
WO2007070395A3 (fr
Inventor
Sam-Shajing Sun
Original Assignee
Norfolk State University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Norfolk State University filed Critical Norfolk State University
Publication of WO2007070395A2 publication Critical patent/WO2007070395A2/fr
Publication of WO2007070395A3 publication Critical patent/WO2007070395A3/fr

Links

Classifications

    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/50—Photovoltaic [PV] devices
    • H10K30/57—Photovoltaic [PV] devices comprising multiple junctions, e.g. tandem PV cells
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/30—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising bulk heterojunctions, e.g. interpenetrating networks of donor and acceptor material domains
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K30/00—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation
    • H10K30/451—Organic devices sensitive to infrared radiation, light, electromagnetic radiation of shorter wavelength or corpuscular radiation comprising a metal-semiconductor-metal [m-s-m] structure
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K71/00—Manufacture or treatment specially adapted for the organic devices covered by this subclass
    • H10K71/10—Deposition of organic active material
    • H10K71/191—Deposition of organic active material characterised by provisions for the orientation or alignment of the layer to be deposited
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/111—Organic polymers or oligomers comprising aromatic, heteroaromatic, or aryl chains, e.g. polyaniline, polyphenylene or polyphenylene vinylene
    • H10K85/114—Poly-phenylenevinylene; Derivatives thereof
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10K—ORGANIC ELECTRIC SOLID-STATE DEVICES
    • H10K85/00—Organic materials used in the body or electrodes of devices covered by this subclass
    • H10K85/10—Organic polymers or oligomers
    • H10K85/151—Copolymers
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
    • Y02E10/00—Energy generation through renewable energy sources
    • Y02E10/50—Photovoltaic [PV] energy
    • Y02E10/549—Organic PV cells

Definitions

  • the present invention relates generally to the field of photovoltaic or photoelectric materials and devices. More particularly, this invention relates to fabricating high efficiency, lightweight, cost effective, and flexible shaped thin film photo detectors and solar cells employing the donor-bridge-acceptor-bridge, or similar type, block copolymers.
  • PV photovoltaic
  • PE photoelectric
  • the 'Fritts Cell was composed of a semiconducting selenium thin layer sandwiched between two different thin layer metal electrodes, one gold layer acting as a large work function electrode (LWFE) and the other metal layer acting as a small work function electrode (SWFE).
  • LWFE large work function electrode
  • SWFE small work function electrode
  • the free electron and hole can easily be separated from each other, even by thermal energy at room temperature, and they can diffuse to the respective and opposite electrodes under a field created by the two different work function metal electrodes.
  • the first organic solar cell the “Tang Cell”
  • the neutral exciton can diffuse randomly in any direction, even under a static electric field.
  • optical gap the material's optical excitation energy gap
  • HOMO Highest Occupied Molecular Orbital
  • LUMO Lowest Unoccupied Molecular Orbital
  • HOMO typically refers to the highest occupied ⁇ orbital(s) (such as ⁇ bonding orbitals at ground state)
  • LUMO refers to the unoccupied ⁇ orbitals (such as ⁇ * anti-bonding orbitals at ground state).
  • HOMO typically refers to the highest occupied ⁇ orbital(s) (such as ⁇ bonding orbitals at ground state) and LUMO refers to the unoccupied ⁇ orbitals (such as ⁇ * anti-bonding orbitals at ground state).
  • optical gap is commonly used here instead of the traditional electronic "band gap” that typically refers to the energy gap between the free holes at valence band (VB) and the free electrons at conduction band (CB) in a semiconducting inorganic material (FIG. 2).
  • E go optical gap
  • E ge electrochemical gap
  • E go — E g ⁇ +E e b exciton binding energy
  • E go values can be conveniently obtained from materials UV-VIS absorption spectra.
  • E ge values may be estimated by electrochemical analysis such as cyclic voltammetry (CV), as described by S. Janietz, et al., "Electrochemical determination of the ionization potential and electron affinity of poly(9,9)- dioctylfluorene," Appl. Phy. Lett., 73, 2453-2455 (1998), incorporated herein by reference.
  • CV cyclic voltammetry
  • the exciton binding energy is about 0.4-0.5 eV, as quoted by T. Stubinger, et al., "Exciton diffusion and optical interference in organic donor-acceptor photovoltaic cells," J. Appl. Phys., 90(7), 3632 (2001), incorporated herein by reference.
  • solar cell applications since solar light radiation spans a wide range yet with largest photo-flux (at 1.5 air mass) in the range of 600-900 nm (1.3-2.0 eV), as quoted by C.
  • an exciton typically will decay (radiatively or non-radiatively) back to ground state at nanoseconds or longer time frames.
  • some excitons may be trapped in solid defect, or "doping," sites. Both of these situations would contribute to the "exciton loss.”
  • an exciton on a conjugated polymer chain can diffuse to a remote site via inter-chain and intra- chain interactions, or coupling.
  • the interaction can be either via hopping or via energy transfer (for a single exciton, for instance, it can be a F ⁇ rster energy transfer process), as described by J.
  • the average exciton diffusion length (limited by the exciton lifetime and the material's morphology) is typically in the range of 10-100 nm, as cited by T. Stubinger, et al. For instance, the average diffusion length for PPV is around 10 nm.
  • the best way to minimize the "exciton loss” would be to build a material with a defect- free tertiary nanosfructure, such that an exciton generated at any site of the material can reach a donor/acceptor interface in all directions within the average exciton diffusion length.
  • One limitation of the "Tang Cell” is that, if the donor or acceptor layer is thicker than the average exciton diffusion length (10-100 nm), then "exciton loss” would be a problem. However, if the photovoltaic active layer thickness is well below the excitation photon wavelength (600-900 nm in the case of a solar cell), then "photon loss” would become a problem. Most importantly, the double layer structure has a relatively small donor/acceptor interface in comparison to blends.
  • the LUMO/HOMO pair difference between the donor and acceptor should not be too large, as that will not only reduce the open circuit voltage (F oc ) that is closely related to the donor HOMO and acceptor LUMO, as reported by CJ. Brabec, et al., in "Origin of the open circuit voltage of plastic solar cells," Adv. Funct. Mater., 11, 374- 380 (2001), incorporated herein by reference. It may also incur ground state electron transfer from the donor HOMO directly to the acceptor LUMO ("chemical doping"). Therefore, an ideal LUMO/HOMO pair difference between the donor and the acceptor appears to be around the exciton binding energy (E e b).
  • Block copolymer approach to photovoltaic functions offers some intrinsic advantages that could hardly be achieved in composite bilayer or blend devices.
  • Block copolymer melts are known to exhibit behavior similar to conventional amphiphilic systems such as lipid-water mixtures, soap, and surfactant solutions, as summarized by M. Lazzari, et ah, in "Block Copolymers for Nanomaterial Fabrication,” Adv. Mater. 15, 1584-1594 (2003), incorporated herein by reference.
  • Another object of the present invention is to provide an improved system for renewable and clean energy generation.
  • Another object of the present invention is to provide an improved, high efficiency system capable of capturing a greater range of energy.
  • Another object of the present invention is to provide a system for converting solar energy into electric energy which reduces or eliminates losses found in previous systems.
  • Yet another object of the present invention is to provide an improved, high efficiency system which is light weight, flexible in shape and cost effective.
  • An improved organic photovoltaic device which consists of a conjugated donor block and a conjugated acceptor block joined together by a non- conjugated bridge.
  • the conjugated donor block has a higher highest occupied molecular orbital and a higher lowest unoccupied molecular orbital than the conjugated acceptor block.
  • the non-conjugated bridge has a highest occupied molecular orbital which is lower than the highest occupied molecular orbital of the conjugated donor block and the conjugated acceptor block and a lowest unoccupied molecular orbital which is higher than the lowest unoccupied molecular orbital of the conjugated donor block and the conjugated acceptor block.
  • the non-conjugated bridge is preferably flexible and formed such that it is able to bend 180°.
  • a plurality of conjugated donor blocks and conjugated acceptor blocks may be alternately joined by non-conjugated bridges and stacked or formed in to columns.
  • the columns are sandwiched by a positive electrode and a negative electrode.
  • a thin donor layer is formed between the positive electrode and the columns and a thin acceptor layer is formed between the negative electrode and the columns.
  • the device is preferably formed a follows. Photovoltaic block copolymer samples are synthesized and then dissolved in a solvent which will preferably dry conveniently. Preferably, the copolymer samples are synthesized by individually synthesizing conjugated donor chains, conjugated acceptor chains and non-conjugated bridge chains, combining the non-conjugated bridge chains with either the conjugated donor chains or the conjugated acceptor chains to form a plurality of bridge-donor- bridge units or bridge-acceptor-bridge units, and combining the formed units with the remaining complimentary conjugated chains. The mixture is then filtered.
  • a film of the filtered mixture is formed on a prepared surface, preferably conducting glass, by spin coating or drop drying or other appropriate method and the solvent is removed by heating, vacuum or a combination. To achieve the desired chain direction, the structure may then be heated and exposed to a magnetic, electrical or optical force.
  • An aspect of the present invention is a tandem style device including a plural or multiple stacked sub-cell pack, preferably with excitation energy gap grading.
  • the tandem device may include a conductive transparent layer interposed between the sub-cells, and preferably includes a transparent electrode at the side receiving incident light and a transparent or opaque electrode at the other side.
  • FIG. 1 shows a simple prior art inorganic semiconductor solar cell, or "Fritts
  • FIG. 2 illustrates energy levels and photo-electric processes in the "Fritts Cell.”
  • FIG. 3 shows a simple prior art organic solar cell, or "Tang Cell.”
  • FIG. 4 illustrates energy levels and inte ⁇ nolecular photo-electric processes in the "Tang Cell.”
  • FIG. 5 shows the "primary structure" of the invented block copolymer.
  • FIG. 6 illustrates energy levels of the invented -DBAB- type block copolymer system.
  • FIG. 7 shows an example of the "secondary structure" of the invented block copolymer thin film.
  • FIG. 8 shows an example of the "tertiary structure" of the invented block copolymer thin film.
  • FIG. 9 shows a first example photovoltaic cell using the invented block copolymer.
  • FIG. 10 shows a second example photovoltaic cell using the invented block copolymer.
  • FIG. 11 shows structures and key synthetic schemes of a specific —DBA- block copolymer already tested.
  • FIG. 12 shows a diagram of a -DBAB- type photovoltaic cell already fabricated and tested.
  • FIG. 13 shows the photo current test results for one fabricated -DBAB- block copolymer photovoltaic cell.
  • FIG. 14 shows the structure of a tandem device using sub-cells of block copolymer photovoltaic.
  • FIG. 15 shows the sub-cell structure.
  • D is a ⁇ electron conjugated donor block with an optical gap matching the desired photon flux and energy (i.e., solar spectra and maximum photon flux range in case of solar cells, or optical signal wavelength in case of photo detectors)
  • A is a conjugated acceptor block, also with an optical gap matching the desired photon energy and maximum flux, and the energy level differences between the donor and acceptor blocks are such that it is just sufficient enough to overcome the exciton binding energy.
  • B is a non-conjugated and flexible bridge unit with a much higher band gap than both the donor and the acceptor blocks, as shown in FIG. 6. Since both the donor and acceptor blocks are ⁇ electron conjugated chains, good carrier transport in both donor and acceptor phases now becomes feasible.
  • a non-conjugated and flexible bridge unit (such as an aliphatic chain containing only ⁇ bonds) is important because: (1) a non-conjugated bridge unit will hinder the intra-chain electron-hole recombination due to the partially insulating nature of organic single bond chains; (2) intra- or inter-molecular energy and electron transfer or electron-hole separation can still proceed effectively through ⁇ bonds or through space under photo-excitations, as shown by M.R. Wasielewski, et al, in "Factoring through-space and through-bond contributions to rates of photoinduced electron transfer in donor-spacer-acceptor molecules," J. Photochem. & Photobiol.
  • ⁇ orbital stacked "secondary structure" has been found to exhibit dramatically enhanced carrier mobility due to improved ⁇ orbital overlapping.
  • a "tertiary structure,” as shown in FIG. 8, where a "HEX” or columnar- type block copolymer morphology is vertically sandwiched between a larger work function positive electrode (e.g., ITO-coated transparent sheet or glass) and a smaller work force function negative electrode e.g., aluminum or calcium) can be realized, as shown in FIG. 9.
  • a larger work function positive electrode e.g., ITO-coated transparent sheet or glass
  • a smaller work force function negative electrode e.g., aluminum or calcium
  • a thin donor layer can be sandwiched between the LWFE and block copolymer layer and a thin acceptor layer can be sandwiched between the SWFE and block copolymer layer, as shown in FIG. 10.
  • This second device structure would enable a desired asymmetry and favorable chemical potential gradient for asymmetric (selective) carrier diffusion and collection under even the two same electrodes. Since the diameter of each donor or acceptor block column can be conveniently controlled via synthesis and processing to be within the typical organic exciton diffusion range of 10-100 nm, every photo-induced exciton will be in convenient reach of a donor/acceptor interface.
  • photo-generated carriers can diffuse more smoothly to their respective electrodes via a truly "bicontinuous" or “channeled” block copolymer "HEX” or related columnar morphology. While the increased donor and acceptor interface size and phase morphology will dramatically minimize the exciton and carrier losses, it nevertheless may also increase the carrier recombination at the same interfaces. However, this charge recombination typically occurs on the microseconds or slower timescale, and this is in contrast to the ultra-fast femto-second charge separation rate at the same interface. Therefore, the charge carrier recombination does not appear to be of a major concern for solar cell applications where the radiation is continuous.
  • the charge recombination may also be minimized by fine-tuning the energy levels of the materials, as the energy level differences also affect charge recombination rate.
  • This block copolymer photovoltaic device may, to a certain degree, minimize a dye- sensitized solar cell (DSSC), as reported by M. Graetzel, et al., in "Molecular Photovoltaics,” Acct. Chem. Res., 33, 269 (2000), incorporated herein by reference, yet with whole donor/acceptor interface covered by photo-sensitizing dyes (band gap matched donor or acceptor units), and that both donor and acceptor phases are solids with good orbital overlap.
  • DSSC dye- sensitized solar cell
  • a -DBAB- or similar analogs such as —DBA-, -DBABD-, -ABDBA-, etc., as shown schematically in FIG. 5, is essential in this invention.
  • Both donor and acceptor are conjugated chain (or block), with the donor having higher LUMO/HOMO levels than the acceptor block, and with the energy level difference preferably closer to the exciton binding energy corresponding to the type of conjugated units, e.g., 0.4-0.5eV for PPV type conjugated polymers.
  • the LUMO/HOMO optical gap of both donor and acceptor preferably match the photon energy, e.g., 1.3 ⁇ 2.0eV in case of solar cell applications.
  • the HOMO/LUMO levels in organic materials can be adjusted via electro-active group substitutions on the conjugated chain.
  • the LUMO/HOMO values may be estimated using certain known theoretical models and calculation methods as described by J.L. Bredas, et al., in "Chain-Length Dependence of Electronic and Electrochemical Properties of Conjugated Systems: Polyacetylene, Polyphenylene, Polythiophene, and Polypyrrole," J. Am. Chem., 105, 6555-6559 (1983), incorporated herein by reference, or may be experimentally measured after the materials are synthesized as elaborated below.
  • the size (or main chain length) of the donor or acceptor conjugated chain should be no shorter than the typical size of an intra-chain exciton corresponding to the type of conjugated units, and no longer than the average exciton diffusion length corresponding to the type of conjugated units, hi PPV for example, the conjugated chain size is preferably between 2-10 nm (corresponding to 3-15 phenylene-vinylene repeating units).
  • the bridge chain should be such that, after coupling with a donor on one end and an acceptor on the other end, at least three consecutive single ( ⁇ ) bonds exist on the bridge chain, and the LUMO level of the bridge is higher than the LUMO of both the donor and acceptor chains, and that the HOMO level of the bridge is lower than the HOMO of both the donor and acceptor chains, as shown in FIG. 6.
  • most aliphatic chains containing only single ( ⁇ ) bonds can satisfy this LUMO/HOMO energy level requirement.
  • a minimum of three consecutive single bonds would not only ensure a non-conjugated large band gap energy barrier between the two conjugated chains, it also enables the bridge a 180° bending capacity from the "primary structure" shape, as shown in FIG.
  • a two-end functionalized donor chain, a two-end functionalized acceptor chain, and a two-end functionalized bridge chain are synthesized first and separately, and the end functional group of each chain should be such that both donor and acceptor chains will react and couple with the bridge chain, yet the donor chain will not react with the acceptor chain and vice-versa, and each chain will not react with itself.
  • Photovoltaic devices can be fabricated as follows: For a first device shown in FIG. 9, the photovoltaic block copolymer samples first may be dissolved in an appropriate solvent that can be conveniently dried. Then the polymer solution needs to be filtered (preferably using a 0.2 micron pore size PTFE filter, i.e., Teflon®) to remove large insoluble particles. The sample solution can then be either spin coated or simply drop dried onto a pre-cleaned India Tin Oxide (ITO) conducting glass slide. The thickness of the thin film can be controlled in a number of ways, such as concentration of the solution, the spin coating speed (in case of spin coating), etc.
  • ITO India Tin Oxide
  • the solvent residue can be removed by heating, exposure to a vacuum, or a combination of both, such as in a heated vacuum oven.
  • the film thickness can be measured using a number of methods or tools; one such method is to use a commercially available profilometer.
  • the thickness of the film needs to be controlled; if the film is too thick, photo-generated carrier loss would become larger, particularly for amorphous thin films without any molecular self-assembly. However, if the film is too thin, photon loss would be more severe as absorption is best when the film thickness is close to the wavelength of the photon. For solar energy applications, since the maximum solar photon flux is between 600-900 nm, an ideal thickness should be in this range.
  • Block copolymer supramolecular structure or morphology is very critical for exciton diffusion, charge separation, and, particularly, carrier transportation.
  • Block copolymer supramolecular structures and morphologies can be manipulated or controlled using a variety of methods. For instance, by using different film forming methods, such as spin coating, drop drying, ink-jet printing, roll-to-roll printing, by changing solvent or concentration, by simple heating after films are dried (also called thermal annealing), and by applying certain external forces such as magnetic, electric, or optical forces. For instance, for the example "secondary structure," as shown in FIG. 7, since the charges (positive and negative) can move more effectively along the conjugated chain direction, the external magnetic fields, electric fields, or polarized light could be a driving force for the preferential alignment of the rigid conjugated chains to the electric field direction.
  • film forming methods such as spin coating, drop drying, ink-jet printing, roll-to-roll printing, by changing solvent or concentration, by simple heating after films are dried (also called thermal annealing), and by applying certain external forces such as magnetic, electric, or optical forces.
  • the external magnetic fields, electric fields, or polarized light could be a
  • FIG. 12 shows an example of a half-ITO covered photovoltaic device fabricated using the above-mentioned protocol.
  • a 20x40 mm sized ITO glass slide was immersed halfway into a concentrated sulfuric acid/chromerge cleaning solution for over 8 hours in order to dissolve part of the ITO covered area completely.
  • the purpose of using a partially covered ITO glass is to avoid a possible electrode touching induced short circuit by creating an aluminum electrode contact area where there is no ITO conducting layer right below. Then the whole ITO glass was submerged briefly into a cleaning solution and was then rinsed with water and ethanol and dried. The ITO slide was then spin coated with approximately 100 nm thick polymer film from a polymer solution.
  • the active area of the photovoltaic cell is defined by the area where aluminum is overlapping with an ITO layer.
  • the active area size may be used to calculate the current density as defined by the total measured current divided by the active area. In this example fabrication, the active area is 10x10 mm.
  • FIG 13 shows the photocurrent density comparison between several photovoltaic cells fabricated from 100 nm thick film of (1) an RO-PPV (donor) and an SF-PPV-I (acceptor) based -DBAB- block copolymer; and (2) RO-PPV/SF-PPV-I equal molar blend; and (3) commercially available MEH- PPV/fiillerenes equal molar blend; and (4) current densities without light radiation (dark current).
  • the light source in this case was a 150 W Xe lamp with a 15x15 mm beam size and a wavelength tunable by a monochromator inside an ISA Fluoromax-3 fluorescence spectrophotometer. The intensity of the light is about 0.01 Sun (i.e., one Sun equals 1000W/m 2 or lOOmW/cm 2 ).
  • the peak photocurrent of the -DBAB- film was almost doubled in comparison to the simple D/A blend. While the shape of the photocurrent versus wavelength reflects both materials' optical (photon) absorptions as well as light intensity variations, the significant photo current magnitude improvement at the same wavelength is a reflection of either (a) the increased donor/acceptor interface; or (b) better film morphology or smoother carrier transportation pathways; or (c) both factors. Thus, even these very preliminary and not yet optimized tests reveal the superiority of this invention.
  • a thin layer (about 1 nm thick) of lithium fluoride (LiF) can be vacuum deposited between the photoactive materials layer and the (metal) negative electrode, and a thin (50-100 run) poly(ethylene dioxythiophene)/polystyrene sulfonic acid (PSS/PEDOT) layer can be spin coated (from an aqueous solution) between the ITO glass and the photoactive materials layer.
  • LiF lithium fluoride
  • PSS/PEDOT poly(ethylene dioxythiophene)/polystyrene sulfonic acid
  • Both LtF and PSS/PEDOT are commercially available and have been known to improve the carrier collection at the respective electrodes, as shown by C. Brabec, et al, in "Organic Photo voltaics: Concepts and Realization," Springer, Berlin (2003), incorporated herein by reference.
  • a second photovoltaic device may also be fabricated, as shown in FIG. 10.
  • a thin donor layer (with thickness less than the average exciton diffusion range, such as 10 nm in case of PPV) is added between the positive electrode and the photovoltaic block copolymer layer, and another thin acceptor layer (also with a thickness less than the average exciton diffusion length) is also added between the photovoltaic block copolymer layer and the negative electrode.
  • a 50-100 nm thick PSS/PEDOT layer can be added between the positive electrode (such as an ITO electrode) and the donor layer, and a 1 nm thick LiF layer can be added between the acceptor layer and the negative electrode layer (such as an Al electrode) in order to enhance carrier collection at both electrodes.
  • the solvent dissolving the donor will not dissolve the dried PSS/PEDOT layer.
  • the same principle is also applicable for the third block copolymer layer in reference to the second donor layer, and to the fourth acceptor layer in reference to the -DBAB- block layer, and so on.
  • this second photovoltaic cell is that the added donor and acceptor layers would create a desire asymmetry (or photo-induced chemical potential gradient) in the photoactive medium itself (without electrodes), so that even if the two electrodes are the same, asymmetric voltage or current would still be generated by light radiation where the donor layer side would gather more photo-generated holes and therefore constitute the positive electrode side, and the acceptor layer would be rich in photo- generated electrons and therefore constitute a negative electrode side.
  • FIG. 14 Another device or aspect is a tandem style photovoltaic device (or PV cell) structure, as shown in Figs 14 and 15, which includes plural or multiple superposed block copolymer sub-cells forming a tandem stack and preferably serially connected.
  • a sub-cell as shown in the embodiment in Fig. 15 is based on the block copolymer, and may comprise two different materials (or phases), one is the p-type semiconductor or organic/polymeric donor type material, and the other is an n-type semiconductor or organic/polymeric acceptor type material.
  • transparent simply means capable of passing a desired quantity and type of light for the application of interest; thus, transparent could encompass a wide variety of transparent or semi-transparent materials or designs.
  • the two materials are preferably assembled in a way as shown in Fig. 15, i.e., in a binary inter-mixed 'columnar' type morphology sandwiched un- symmetrically between a p-type (or donor) thin layer and a n-type (or acceptor) thin layer, where the diameter of each column should preferably not be substantially longer then the average exciton diffusion length (AEDL).
  • AEDL average exciton diffusion length
  • the AEDL is defined as the average distance a photo excited exciton travels before relaxing back to ground state.
  • Such an un-symmetrically sandwiched 'columnar' type morphology may be achieved by a number of methods, such as using -donor-bridge-acceptor-bridge- type conjugated block copolymers as described above, or other binary nano structure fabrication methods, such as those described by B. Sager, et al. in U.S. Pub. No. 2004-0250848, by J. Whiteford, et al. in U.S. Pub. No. 2004-0146560, by M. Roscheisen in U.S. Pub. No. 2005-0098204, by B. Sager, et al. in U.S. Pub. No. 2005- 0121068, etc., all of which are incorporated by reference.
  • the sub-cells are preferably serially connected and stacked to each other as shown in Fig. 14, and with P- (or N-) terminal layers facing the same direction. Additionally, a thin transparent (or semi transparent) and conductive layer (TCL) is preferably interposed between each of the sub-cell units.
  • the side directed to incident radiating light includes the transparent electrode or T-ET, which is followed by the sub-cells as shown in Fig. 14.
  • Energy gap grading may be used to improve efficiency.
  • the donor or acceptor has only one energy gap and can only efficiently capture a narrow or limited range of energy matched photons.
  • a tandem configuration enables the ordering or grading of average excitation energy gaps among the plurality of sub-cells to span a broader range of the energy spectrum.
  • the average excitation energy gap of each sub-cell (i.e., defined as the average value of the optical excitation energy gaps of both the donor and the acceptor) is graded or configured in generally descending order - from larger energy gap (i.e., at the incident sub-cell) to smaller energy gap (i.e., along the residual sub-cells).
  • the range of the grading of sub-cell energy gaps preferably approximates the range of the electromagnetic radiation for the PV device to be used.
  • the solar photon flux energy spectrum defines a maximum energy level of about 3 eV and a minimum energy level of about 0.5 eV.
  • the largest average energy gap of the incident sub-cell i.e. closest to T-ET side
  • the smallest average energy gap of the final residual sub-cell i.e., closest to TO-ET side
  • the incident sub-cell, having the largest average energy gap would capture the highest energy matched photons first, but also would allow residual lower energy photons to pass through to the subsequent residual sub-cells having lower energy gaps, and so on.
  • a generally decreasing average energy gap enables photon capture along the desired energy spectrum.
  • the p- (or donor) side of all sub-cells should generally face the direction of the electrode having the larger work function (i.e., the electrode with a more negative energy level below the vacuum energy level at zero.)
  • the work function is defined as the average energy needed to remove one electron from the material.
  • the positive electrode of the device (where positively charged holes will be collected when light is radiated to the device) is the electrode where the p- or donor side of the sub-cell units are . facing
  • the negative electrode of the device (where negatively charged electrons will be collected when light is radiated to the device) is the electrode where the n- or acceptor side of the sub-cell units are facing.
  • the —donor-bridge-acceptor— type block copolymer disclosed herein is a significant difference or improvement over small molecule donor-bridge-acceptor approaches.
  • the use of block copolymer enables secondary and tertiary structures or morphologies for improved photo charge separation and charge transport.
  • the carrier generation and transport in each sub-cell of the tandem photovoltaic device is improved due to the ordered nano structure, as elaborated herein.
  • Excitation energy gap grading among the stacked multiple sub-cells also enhances the ability for photon capture of broader spectrum of radiation (e.g., sunlight radiation).
  • This contemplated arrangement may be achieved in a variety of configurations.

Abstract

L'invention concerne un système de copolymère séquencé de type donneur(D)-pont(B)-accepteur(A)-pont(B) ou de type dérivé, utilisé dans un dispositif tandem constitué de plusieurs sous-cellules, dans lequel le donneur (D) est un bloc organique conjugué donneur (de type P), l'accepteur (A) est un bloc organique conjugué accepteur (de type N) et le pont (B) est une chaîne non conjuguée et flexible. Le système de copolymère a été conçu et testé préalablement pour des applications éventuelles dans des cellules solaires ou des photodétecteurs 'en matière plastique' à film mince de poids réduit, de forme souple, peu coûteux et à haut rendement. On s'attend à ce qu'une 'structure tertiaire supramoléculaire à nanophases séparées' dérivée de ce copolymère séquencé -DBAB- améliore de manière significative le rendement de transformation d'énergie optoélectronique (photovoltaïque) par rapport à tous les systèmes photovoltaïques organiques ou polymères de donneur/accepteur existants grâce la réduction des 'pertes par excitons', des 'pertes par porteurs' ainsi que les 'pertes par photons' suite à l'optimisation de la morphologie dans l'espace à trois dimensions et des niveaux d'énergie. L'empilement en tandem de sous-cellules de copolymère séquencé permet en outre d'échelonner le puits d'énergie d'excitation optique de manière à améliorer la capture des photons dans le spectre solaire ainsi que le rendement du dispositif.
PCT/US2006/046951 2005-12-12 2006-12-11 Dispositifs photovoltaiques tandem bases sur un nouveau copolymere sequence WO2007070395A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
US74942905P 2005-12-12 2005-12-12
US60/749,429 2005-12-12

Publications (2)

Publication Number Publication Date
WO2007070395A2 true WO2007070395A2 (fr) 2007-06-21
WO2007070395A3 WO2007070395A3 (fr) 2008-01-03

Family

ID=38163432

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/US2006/046951 WO2007070395A2 (fr) 2005-12-12 2006-12-11 Dispositifs photovoltaiques tandem bases sur un nouveau copolymere sequence

Country Status (1)

Country Link
WO (1) WO2007070395A2 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010060159A1 (fr) * 2008-11-28 2010-06-03 The University Of Melbourne Nouveaux copolymères séquencés, procédés de préparation et leur utilisation au sein de dispositifs à hétérojonction

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5261969A (en) * 1992-04-14 1993-11-16 The Boeing Company Monolithic voltage-matched tandem photovoltaic cell and method for making same
US6414235B1 (en) * 1999-03-30 2002-07-02 Daniel Luch Substrate and collector grid structures for integrated series connected photovoltaic arrays and process of manufacture of such arrays
US20040099307A1 (en) * 2002-11-14 2004-05-27 Sam-Shajing Sun Photovoltaic devices based on a novel block copolymer

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5261969A (en) * 1992-04-14 1993-11-16 The Boeing Company Monolithic voltage-matched tandem photovoltaic cell and method for making same
US6414235B1 (en) * 1999-03-30 2002-07-02 Daniel Luch Substrate and collector grid structures for integrated series connected photovoltaic arrays and process of manufacture of such arrays
US20040099307A1 (en) * 2002-11-14 2004-05-27 Sam-Shajing Sun Photovoltaic devices based on a novel block copolymer

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2010060159A1 (fr) * 2008-11-28 2010-06-03 The University Of Melbourne Nouveaux copolymères séquencés, procédés de préparation et leur utilisation au sein de dispositifs à hétérojonction

Also Published As

Publication number Publication date
WO2007070395A3 (fr) 2008-01-03

Similar Documents

Publication Publication Date Title
US20090084444A1 (en) Photovoltaic devices based on a novel block copolymer
US20070095391A1 (en) Tandem photovoltaic devices based on a novel block copolymer
Pitchaiya et al. A review on the classification of organic/inorganic/carbonaceous hole transporting materials for perovskite solar cell application
Wang et al. The principles, design and applications of fused-ring electron acceptors
Wang et al. Carbon nanotube-based heterostructures for solar energy applications
Sun et al. Organic solar cell optimizations
Tepavcevic et al. Improved hybrid solar cells via in situ UV polymerization
TWI709249B (zh) 具有激子障蔽性電荷載體濾波器之有機光敏性裝置
US8269100B2 (en) Hybrid solar cells via UV-polymerization of polymer precursor
US20090084436A1 (en) Effective organic solar cells based on triplet materials
EP3039729A1 (fr) Traitements de blocage d'exciton pour des couches tampons dans des photovoltaïques organiques
TWI661587B (zh) 發電彩色塗料
Troshin et al. Organic solar cells: structure, materials, critical characteristics, and outlook
Tarique et al. A review of progress and challenges in the research developments on organic solar cells
EP2875534A1 (fr) Dispositifs photovoltaïques organiques multijonction incorporant des couches actives déposées en solution et sous vide
Sun et al. Optimization of Organic Solar Cells in Both Space and Energy–Time Domains
WO2010090123A1 (fr) Élément de conversion photoélectrique organique, cellule solaire l'utilisant, et réseau de détecteur optique
Sun et al. Sunlight energy conversion via organics
TWI660532B (zh) 具有激子障蔽性電荷載體濾波器之有機光敏性裝置
JP5944120B2 (ja) 有機光電変換素子とその製造方法、およびそれを用いた有機太陽電池
TWI684296B (zh) 具有採用高玻璃轉換溫度材料之激子障蔽性電荷載體濾波器之穩定性有機光敏性裝置
Beek et al. Hybrid polymer-inorganic photovoltaic cells
WO2007070395A2 (fr) Dispositifs photovoltaiques tandem bases sur un nouveau copolymere sequence
FR2932002A1 (fr) Systeme optimise de production d'energie solaire avec double chambre de capture muni de cellules photovoltaiques et de compartiment de capture et d'echange thermique a base des nano particules
Selvakumar et al. A review on the classifications of organic/inorganic/carbonaceous hole transporting materials for perovskite solar cell application

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 06839240

Country of ref document: EP

Kind code of ref document: A2