Creation of high-efficiency, toxic- and rare-element-free thin-film solar cells by defect control

2023 Fiscal Year Final Research Report

• Project/Area Number: 20H02680
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Review Section: Basic Section 31020:Earth resource engineering, Energy sciences-related
• Research Institution: Nagaoka University of Technology
• Principal Investigator: Tanaka Kunihiko 長岡技術科学大学, 工学研究科, 教授 (30334692)
• Co-Investigator(Kenkyū-buntansha): 荒木 秀明 長岡工業高等専門学校, 物質工学科, 教授 (40342480)
• Project Period (FY): 2020-04-01 – 2024-03-31
• Keywords: 環境調和半導体 / 薄膜太陽電池 / 半導体光物性 / 発光スペクトル

Outline of Final Research Achievements

Solar cells which absorption layer is Cu2SnS3 (CTS) and Cu2Sn1-xGexS3 (CTGS) can be highly efficient, non-toxic, rare-element-free, environmentally friendly, and low-cost solar cells. However, the current power conversion efficiency of CTS and CTGS solar cells is much lower than the theoretical efficiency. In order to obtain a guideline for improving the efficiency, the defects that contribute to the efficiency reduction or improvement were investigated by observation of photoluminescence(PL). The defects revealed by PL observation are shallower than room temperature and are not a cause of efficiency reduction, and may contribute to efficiency improvement as a carrier supply source. In addition, the depth of shallow defects hardly changed with Ge content. Those facts indicate that CTS and CTGS are excellent as a solar cell light absorbing layer material.

Free Research Field

半導体光物性

Academic Significance and Societal Importance of the Research Achievements

Cu2SnS3(CTS)、Cu2Sn1-xGexS3(CTGS)は太陽電池光吸収層材料として注目されているものの、太陽電池素子作製の研究が中心であり発電効率に大きな影響を与える欠陥の研究はあまり進んでいない。特に発光分光観測による欠陥の解析はほとんど行われていない。本研究では発光分光により発電効率に影響を与える欠陥に関する知見を新たに得ることができた。したがってCTS、CTGS薄膜太陽電池の高効率化に対する有益な情報を提供できたといえる。