Formation of Native Inx(O, S)y Buffer through Surface Oxidation of Cu(In, Ga)(S, Se)2 Absorber for Significantly Enhanced Conversion Efficiency of Flexible and Cd‐Free Solar Cell by All‐Dry Process. Issue 7 (4th April 2022)

• Record Type: Journal Article
• Authors: Chantana, Jakapan; Kawano, Yu; Nishimura, Takahito; Mavlonov, Abdurashid; Negami, Takayuki; Minemoto, Takashi
• Is Part Of: Solar RRL. Volume 6:Issue 7(2022)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2022-04-04
• Subjects: air-annealing process -- flexible Cu(In, Ga)Se2 solar cell -- native Inx(O, S)y buffer -- stainless steel substrate -- surface oxidation; Solar energy -- Periodicals; Photovoltaic power generation -- Periodicals; Solar energy -- Research -- Periodicals; Photovoltaic power generation -- Research -- Periodicals; Periodicals; 333.7923
• DOI: 10.1002/solr.202200250
• Languages: English
• ISSNs: 2367-198X

Abstract

Abstract : Herein, flexible, Cd‐free, and all‐dry process Cu(In, Ga)(S, Se)2 (CIGSSe) solar cells on stainless steel (SUS) substrates are developed with manufacturing CIGSSe absorbers fabricated in real production line with large sample size of 0.94 × 1.23 m 2 . Air‐annealing process under a temperature of 130 °C, 1 atmospheric pressure, and air humidity of about 50% (accelerated oxidizing process) is conducted on absorbers for their oxidized surface. It is demonstrated for the first time that oxidized surface of CIGSSe absorbers after air‐annealing process gives rise to considerable increases in photovoltaic performances of CIGSSe solar cells. This occurs because of formation of native In x (O, S) y buffer near CIGSSe surface formed after air‐annealing process, which yields self‐forming heterojunction, acting as charge separation and hole‐blocking barrier with increased valence band offset of native In x (O, S) y /CIGSSe to 1.4 eV, thereby avoiding sputtering damage on CIGSSe surface. Therefore, carrier recombination rates at the interface and depletion regions of the solar cell are reduced, implying improvement of interface and near‐surface qualities. Ultimately, conversion efficiency of 16.7% for flexible, Cd‐free, and all‐dry process CIGSSe solar cell on SUS substrate is attained after the air‐annealing process (130 °C and 6 h) with potential toward Lab‐to‐Fab transition. Abstract : Native In x (O, S) y buffer near Cu(In, Ga)(S, Se)2 (CIGSSe) surface formed after air‐annealing process gives rise to self‐forming heterojunction, acting as charge separation and hole‐blocking barrier with different valence band offset (Δ E V ) of native In x (O, S) y /CIGSSe to 1.4 eV. Herein, efficiency of 16.7% for flexible, Cd‐free, and all‐dry process CIGSSe solar cell on SUS substrate is ultimately attained with potential toward Lab‐to‐Fab transition.