Development of high efficiency Indium-free compound thin film solar cell by band engineering

2019 Fiscal Year Final Research Report

• Project/Area Number: 16H04336
• Research Category: Grant-in-Aid for Scientific Research (B)
• Allocation Type: Single-year Grants
• Section: 一般
• Research Field: Electronic materials/Electric materials
• Research Institution: Nagaoka National College of Technology
• Principal Investigator: Araki Hideaki 長岡工業高等専門学校, 物質工学科, 教授 (40342480)
• Project Period (FY): 2016-04-01 – 2020-03-31
• Keywords: 太陽電池 / 硫化物 / バンドギャップ制御 / 薄膜 / カルコゲン化合物 / インジウムフリー / 銅錫ゲルマニウム硫化物

Outline of Final Research Achievements

In this study, a quaternary semiconductor material namely, Cu2(Sn,Ge)S3, which does not contain the rare element In or the toxic element Se, has been considered as a light absorption layer material for solar cells. The synthesis of Cu2(Sn,Ge)S3 and evaluation of its physical properties were carried out. In addition, the study focused on the development of Cu2(Sn,Ge)S3 thin film fabrication technology. Bulk crystal samples of Cu2(Sn,Ge)S3 were synthesized. The dependence of the crystal structure and band gap on the composition ratio of Ge/(Ge+Sn) was clarified. Heterojunction solar cells with Cu2(Sn,Ge)S3 thin films having different composition ratios of Ge/(Sn+Ge) and a CdS buffer layer were fabricated. The dependence of the external quantum efficiency on the film composition was demonstrated.

Free Research Field

電子・電気材料工学

Academic Significance and Societal Importance of the Research Achievements

次世代太陽電池としてCu(In,Ga)(S,Se)2やCdTeなどの省資源な薄膜光吸収材料が注目されているが，希少元素や毒性を使用しており，環境負荷や資源の枯渇が懸念され，希少元素Inや毒性元素Seを含まない高効率太陽電池材料の開発が重要な課題となっている。本研究は，将来の太陽電池材料の新たな候補として，In資源の制約を受けないInフリー硫化物系薄膜太陽電池材料であるCu2(Sn,Ge)S3を用いた薄膜太陽電池の実現を目指して基礎研究を推進したものであり，いくつかの重要な基礎的知見を得ることができた。