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US-20260130042-A1 - Multilayer Back Contacts for Perovskite Photovoltaic Devices

US20260130042A1US 20260130042 A1US20260130042 A1US 20260130042A1US-20260130042-A1

Abstract

Photovoltaic devices having contact layers are described herein. Devices, intermediate structures, and methods for making multilayer contacts for perovskite photovoltaic devices are provided. Embodiments include materials and methods for forming back contacts.

Inventors

  • Joseph Jonathan Berry
  • Kai Zhu
  • Le Chen
  • Axel Finn Palmstrom
  • Tze-Bin Song
  • Vera Steinmann
  • Natasha Teran
  • Aravamuthan Varadarajan
  • Xueping Yi
  • Zhibo Zhao

Assignees

  • FIRST SOLAR, INC.
  • Alliance for Energy Innovation, LLC

Dates

Publication Date
20260507
Application Date
20260105

Claims (19)

  1. 1 . A method of making a photovoltaic device comprising: forming an absorber layer over a substrate stack, wherein the absorber layer comprises a perovskite material; depositing a hole transport layer over the absorber layer; and forming a multilayer back contact layer by: depositing a buffer sublayer over the hole transport layer, wherein the depositing is performed at a temperature below 200 C; depositing a barrier sublayer over the buffer sublayer; and depositing a conductor sublayer over the barrier layer.
  2. 2 . The method of claim 1 , wherein the conductor sublayer, comprises at least one metal; the barrier sublayer is between the hole transport layer and the conductor sublayer; the barrier sublayer comprises at least one of: a transition metal nitride or a metal oxynitride; the buffer sublayer is adjacent to the hole transport layer; the buffer sublayer comprises at least one of: a metal oxide or a metal oxynitride; the buffer sublayer has a composition different from the barrier sublayer; the buffer sublayer is disposed between the hole transport layer and the barrier sublayer; and the buffer sublayer has a thickness less than or equal to 30 nm.
  3. 3 . The method of claim 1 , wherein the step of depositing a buffer sublayer comprises thermal evaporation of molybdenum oxide (MoO x ), bismuth telluride (Bi 2 Te 3 ), vanadium oxide (VO x ), or tungsten oxide (WO x ).
  4. 4 . The method of claim 1 , wherein the buffer sublayer comprises a metal oxynitride; the buffer sublayer has a thickness less than or equal to 25 nm, and the buffer sublayer has a work function in a range from 5 eV to 10 eV.
  5. 5 . The method of claim 1 , wherein forming a multilayer back contact layer comprises: depositing a protective sublayer comprising chromium over the conductor sublayer.
  6. 6 . A method of making a back contact layer for a photovoltaic device comprising: forming a multilayer back contact layer by: depositing a buffer sublayer over a charge transport layer, wherein the depositing is performed at a temperature below 200 C; depositing a barrier sublayer over the buffer sublayer; and depositing a conductor sublayer over the barrier layer.
  7. 7 . The method of claim 6 , wherein: the buffer sublayer has a thickness less than or equal to 30 nm; the buffer sublayer comprises a metal oxide or a metal oxynitride; the barrier sublayer disposed adjacent to the buffer sublayer; the barrier sublayer has a thickness less than or equal to 50 nm; and the barrier sublayer comprises a transition metal nitride or a metal oxynitride; and the buffer sublayer has a composition different from the barrier sublayer.
  8. 8 . The method of claim 7 , wherein the step of depositing a buffer sublayer comprises thermal evaporation of molybdenum oxide (MoO x ), bismuth telluride (Bi 2 Te 3 ), vanadium oxide (VO x ), or tungsten oxide (WO x ).
  9. 9 . The method of claim 7 , wherein: the charge transport layer is a hole transport layer; the buffer sublayer is disposed adjacent to the hole transport layer; and the hole transport layer is provided over a perovskite absorber layer.
  10. 10 . The method of claim 9 , wherein the hole transport layer comprises at least one of: PTAA, P3HT, P3HT-COOH, PEDOT:PSS, TTF-1, SGT-407, SpiroOMeTAD, NiOx, CuSCN, or CuI.
  11. 11 . The method of claim 9 , wherein the buffer sublayer has a thickness of 0.5 nm to 25 nm in a contiguous film over the hole transport layer.
  12. 12 . The method of claim 7 , wherein the buffer sublayer comprises a metal oxynitride; the buffer sublayer has a thickness less than 25 nm, and the buffer sublayer has a work function in a range from 5 eV to 10 eV.
  13. 13 . The method of claim 6 , wherein the step of depositing a buffer sublayer is performed by at least one of: thermal evaporation, spray pyrolysis, closed space sublimation (CSS), chemical vapor deposition (CVD), atomic layer deposition (ALD), spin coating, spray coating, slot-die coating, blade coating, roll coating, dip coating, or sol-gel.
  14. 14 . The method of claim 6 , wherein the step of depositing a buffer sublayer comprises thermal evaporation of tungsten oxide (WO x ).
  15. 15 . The method of claim 6 , wherein: the step of depositing a barrier sublayer is performed by sputtering.
  16. 16 . The method of claim 6 , wherein: the step of depositing a conductor sublayer is performed by sputtering, and the conductor sublayer comprises at least one metal.
  17. 17 . The method of claim 6 , wherein: the buffer sublayer comprises at least one of: molybdenum oxide, bismuth telluride, or vanadium oxide; and the barrier sublayer comprises at least one of: molybdenum nitride (MoN x ), aluminum oxide (Al 2 O 3 ), silicon oxide (SiO 2 ), silicon oxynitride (SiNO x ), titanium nitride (TiN x ), chromium nitride (CrN x ), tin oxide (SnO x ), tin-gallium oxide (GaOSn), aluminum nitride (AlN), nickel nitride (Ni 3 N), titanium nitride (TiN), tungsten nitride (WN x ), selenium nitride (SeN x ), tantalum nitride (TaN), vanadium nitride (VN), molybdenum oxynitride (MoN x O y ), or zirconium oxynitride (ZrO x N y ).
  18. 18 . A back contact for a perovskite photovoltaic device, having a perovskite absorber layer and a charge transport layer, the back contact comprising: a buffer sublayer disposed adjacent to the charge transport layer; wherein, the buffer sublayer has a thickness less than or equal to 25 nm; the buffer sublayer comprises a metal oxide or a metal oxynitride; a barrier sublayer disposed adjacent to the buffer sublayer; wherein, the barrier sublayer has a thickness less than or equal to 50 nm; the barrier sublayer has a composition different from the buffer sublayer; the barrier sublayer comprises a transition metal nitride or a metal oxynitride; and a conductor sublayer disposed over the buffer sublayer.
  19. 19 . The back contact layer of claim 18 , wherein: the buffer sublayer comprises at least one of: molybdenum oxide, bismuth telluride, or vanadium oxide; and the barrier sublayer comprises at least one of: molybdenum nitride, tin oxide, silicon oxide, silicon oxynitride, titanium nitride, or chromium nitride.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application is a divisional application of U.S. application Ser. No. 18/277,157, which entered the national phase on Aug. 14, 2023, a national phase of international application PCT/US2022/016145, filed on Feb. 11, 2022, and claims the benefit of U.S. Provisional Application 63/149,060, filed on Feb. 12, 2021, each of which is incorporated by reference in the entirety. STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH This invention was made under a Cooperative Research and Development Agreement, CRADA #CRD-13-507, between First Solar, Inc. and the National Laboratory of the Rockies, formerly known as the National Renewable Energy Laboratory, operated for the United States Department of Energy by the Alliance for Energy Innovation, LLC. The United States Government has rights in this disclosure under Contract No. DE-AC36-08GO28308 between the United States Department of Energy and the Alliance for Energy Innovation, LLC, formerly, Alliance for Sustainable Energy, LLC, the Manager and Operator of the National Laboratory of the Rockies. The government has certain rights in this invention. BACKGROUND The present specification generally relates to layers for photovoltaic devices and, more specifically, to the use of particular combinations of materials, layer structures, and layer formation parameters to provide efficient back contacts for use in N-I-P structured perovskite photovoltaic devices. A photovoltaic device generates electrical power by converting light into electricity using semiconductor materials that exhibit the photovoltaic effect. Perovskites are a class of materials which may form an active layer in photovoltaic devices. Perovskite compounds have an ABX3 structure, where A and B are cations and X is a halide. Materials including lead halide and tin halide perovskite compounds have been studied for use in photovoltaic devices. In these structures, the A site may be composed of one or more cations, such as methylammonium (MA), formamidinium (FA), cesium (Cs+), or rubidium (Rb+). The B site may be occupied, for example, by one or more of lead (Pb+2), tin (Sn+2), or germanium (Ge+2) cations. And the X site may be occupied by one or more halogen anions, such as iodine (I−), bromine (Br−), or chlorine (Cl−). In a photovoltaic device, the perovskite material is positioned in contact with and between an electron charge transport layer (ETL) and hole charge transport layer (HTL). Perovskite solar cells can degrade when exposed to moisture, oxygen, heat, light, mechanical stress, and reverse bias. Heat can volatilize halide species from the perovskite complex, and light exposure can enhance halogen mobility, promoting reactions with metal contacts. Most metals are susceptible to react with halogens or halide species, potentially causing corrosion, instability, or diminished efficiency. Existing back contacts or conductive layers applied over hole-transport layers in metal-halide perovskite solar cells include materials such as silver (Ag) and gold (Au), which are expensive and contribute to instability. Alternate materials, such as alloys of aluminum (Al) and copper (Cu) also have significant stability issues. Perovskite semiconductor materials and materials used for hole transport layers can be damaged by high-temperature processing steps, constraining options for the materials and deposition methods for use in producing perovskite-based photovoltaic devices. Accordingly, a need exists for alternative layer structures, compositions, and processing methods to provide efficient back contacts in perovskite photovoltaic devices. BRIEF DESCRIPTION OF THE DRAWINGS The embodiments set forth in the drawings are illustrative and exemplary in nature and not intended to limit the subject matter defined by the claims. The following detailed description of the illustrative embodiments can be understood when read in conjunction with the following drawings, wherein like reference numerals designate identical or corresponding parts throughout the views. The patent or application file may contain at least one drawing executed in color and/or one or more photographs. Copies of this patent or patent application publication with color drawings will be provided by the Patent Office upon request and payment of the necessary fee. FIG. 1 schematically depicts a cross-sectional view of a segment of a photovoltaic device according to one or more embodiments shown and described herein; FIG. 2 schematically depicts a cross-sectional view of a first embodiment of a back contact layer of the photovoltaic device of FIG. 1; FIG. 3 schematically depicts a cross-sectional view of a second embodiment of a back contact layer of the photovoltaic device of FIG. 1; FIG. 4 shows a flow chart for an example method for making a photovoltaic device according to one or more embodiments shown and described herein; FIG. 5 shows a portion of a perovskite device with degradation; FIG. 6 shows a comparison o