低温プロセスで安定かつ高効率なCuInS2太陽電池、効率12%以上を達成（Low-Temperature Processed Stable and Efficient CuInS2 Solar Cell Delivers Over 12% Efficiency）

2026-04-08 合肥物質科学研究院（HFIPS）

CuInS₂ thin-film solar cell fabricated by low-temperature solution-processing strategy delivers new records of efficiency and open-circuit voltage. (Image by ZHANG Chaofan)

＜関連情報＞

• https://english.hf.cas.cn/nr/rn/202604/t20260408_1155377.html
• https://www.cell.com/joule/abstract/S2542-4351(26)00002-4

12%を超える効率を持つCuInS₂太陽電池を低温で製造する戦略 A low-temperature strategy to prepare CuInS2 solar cells with efficiency exceeding 12%

Wenbo Cao ∙ Chao Dong ∙ Dongxing Kou ∙ … ∙ Yingying Dong ∙ Chong Chen ∙ Mingtai Wang
Joule  Published:March 6, 2026
DOI:https://doi.org/10.1016/j.joule.2026.102318

Context & scale

Photovoltaic (PV) conversion of solar energy into electricity is an up-and-coming renewable way to generate sustainable energy. Nowadays, PV development still remains constrained by the challenging demand for low-cost, stable, and efficient solar cells. The pursuit of such high-performance solar cells inspires the solution-processing approaches, which mainly involve a film matrix formation by facile technologies (e.g., spin-coating, doctor blading, screen printing, and inkjet printing) and a subsequent post-annealing at a low temperature (normally ≤ 500°C), to fabricate inorganic heterojunction films for stable and efficient solar cells. CuInS₂ is a promising light-absorbing material because of its optimal band gap, large absorption coefficient, and eco-friendly elements. However, after the state-of-the-art efficiency of 12.2% was obtained at 600°C in 1996, the development of CuInS₂ solar cells has been stagnating for nearly three decades.

In this work, a low-temperature (< 300°C) solution-processing strategy featuring the combination of an interdigitation structure and a sulfur anion-induced gradient phase transformation (S²⁻-GPT) is developed to fabricate efficient CuInS₂ solar cells. Interdigitating electron-extracting interfaces into an In-rich CuInS₂ absorber layer allows a much thicker CuInS₂ layer with a high specific surface area of charge-separating interfaces to guarantee the high light absorption, charge generation, and charge extraction/spatial separation, while the S²⁻-GPT process improves the CuInS₂ layer quality by reducing deep-level defects and enhancing charge collection efficiency for boosting total photovoltaic parameters. These findings demonstrate a low-temperature avenue with detailed principles for efficient CuInS₂ solar cells that meet the essential requirements of the practical application on a large scale. In the long term, combining interdigitation structures and S²⁻-GPT processes in absorber layers offers a conceptual way to prepare solution-processed efficient chalcogenide solar cells.

Highlights

• The breakthrough efficiency of 12.28% is achieved in CuInS₂ solar cells at < 300°C
• Absorber layer interdigitated by electron-extracting interfaces favors solar cells
• S²⁻-GPT takes place in an In-rich CuInS₂ layer at a low temperature of 180°C
• Each phase transformation in the S²⁻-GPT process occurs locally in a short range

Summary

Copper indium sulfide (CuInS₂) is a promising absorber among emerging chalcogenide photovoltaics. However, solution-processed CuInS₂ solar cells at low temperature (< 400°C) still lag far behind the requirement of at least 10% efficiency for practical application since 1993. Here, a low-temperature strategy, featuring a solution-processed In-rich CuInS₂ film interdigitated with electron-extracting interfaces and a sulfur anion-induced gradient phase transformation (S²⁻-GPT) process at < 200°C, is conceptually developed for preparing the CuInS₂ solar cells with a breakthrough efficiency up to 12.28%. The interdigitated structure has unique advantages over the simple bilayer structure conventionally used; moreover, the S²⁻-GPT process leads to the transformation from CuAu to CuIn₅S₈ phase to reduce the defect density and charge recombination inside CuInS₂ film for boosting solar cell performance. The detailed principles behind material and device are elucidated. Our findings offer a promising way to chalcogenide solar cells and the application of CuInS₂ devices.