Development of defect evaluation method for photoabsorption layer in compound thin film solar cells and evaluation using it

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K06345
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Electronic materials/Electric materials
• Research Institution: Gifu University
• Principal Investigator: ITOH Takashi 岐阜大学, 工学部, 教授 (00223157)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: 太陽電池 / 光吸収 / 欠陥評価

Outline of Final Research Achievements

In this study, We developed a method to evaluate defects from photo-absorption for the photo-absorption layer in compound thin film solar cells using Fourier transform photocurrent spectroscopy (FTPS). We also evaluated Cu2ZnSn(S,Se)4(CZTSSe) solar cell using it. The exponential tail was observed in the photon-energy region smaller than the band gap energy of CZTSSe. The exponential tail would be related to antisite point defects of Cu and Zn. Furthermore, absorption near 1.3eV was observed through the FTPS measurement of CZTSSe solar cell under bias light irradiation. This absorption would be related to gap-state defect induced by bias light irradiation and would cause decrease of quantum efficiency in the high photon-energy region under the irradiation of white bias light.

Free Research Field

電気電子材料工学

Academic Significance and Societal Importance of the Research Achievements

薄膜太陽電池光吸収層の欠陥を太陽電池構造のまま評価である本評価技術は、高効率化合物薄膜太陽電池だけでなく、ペロブスカイト太陽電池など他の高効率薄膜太陽電池の迅速な開発に貢献できる。また、本研究ではCZTSSeのバンドギャップ内の欠陥準位に関する新たな知見が得られており、CZTSSe太陽電池の高効率化だけでなく、CZTSSeの物性理解につながる。以上の点に、学術的意義と社会的意義があると考えられる。