Enhancement of photovoltaic performances of Cu (In,Ga)(S,Se)2 solar cell through combination of heat‐light soaking and light soaking processes

• Published in: Progress in photovoltaics Vol. 26; no. 10; pp. 868 - 876
• Main Authors: Chantana, Jakapan, Kato, Takuya, Sugimoto, Hiroki, Minemoto, Takashi
• Format: Journal Article
• Language: English
• Published: Bognor Regis Wiley Subscription Services, Inc 01.10.2018
• Subjects: Carrier density; Conduction bands; Copper; Cu (In,Ga)(S,Se)2; Energy conversion efficiency; heat‐light soaking; Illumination; Light; light soaking; Performance enhancement; Photovoltaic cells; recombination rate; Silicon wafers; Soaking; Solar cells; thin‐film solar cell
• ISSN: 1062-7995; 1099-159X
• DOI: 10.1002/pip.3031

Potassium‐treated Cu (In,Ga)(S,Se)2 (CIGSSe)‐based solar cell with power conversion efficiency (η) of 19.4% is obtained using high transparent Cd0.75Zn0.25S/Zn0.79Mg0.21O/Zn0.88Mg0.12O:Al layers to minimize optical loss at short wavelength (~520 nm) and to control total conduction band minimum alignment. To further enhance η, the post treatment named HLS + LS process, including heat‐light soaking (HLS) at 110°C under AM 1.5G illumination followed by light soaking (LS) under AM 1.5G illumination, is conducted successively on the as‐fabricated solar cell. It is revealed that HLS in the HLS + LS process mainly yields the increase in open‐circuit voltage. On the other hand, LS in the HLS + LS process primarily leads to the increase in fill factor, attributable to the decrease in sheet resistance of Zn0.88Mg0.12O:Al. The HLS + LS process consequently gives rise to not only the enhancement of carrier concentration but also the decrease in the recombination rate at the buffer/absorber interface through passivating the recombination centers. As a result, 21.2%‐efficient CIGSSe solar cell with the Cd0.75Zn0.25S/Zn0.79Mg0.21O/Zn0.88Mg0.12O:Al layers is attained after the HLS + LS process, which is an effective process to enhance photovoltaic performances. Heat‐light soaking + light soaking (HLS + LS) process (posttreatment), including heat‐light soaking (HLS) at 110°C followed by light soaking (LS) under AM 1.5G illumination, are conducted on potassium‐treated Cu (In,Ga)(S,Se)2‐based solar cell to enhance conversion efficiency up to 21.2%, where the HLS of the HLS + LS process increases open‐circuit voltage, whereas the LS of the HLS + LS process enhances fill factor. It is moreover revealed that the HLS + LS process gives rise to not only enhancement of carrier concentration but also decrease in recombination rate at buffer/absorber interface.