Role of anions in aqueous sol-gel process enabling flexible Cu(In,Ga)S2 thin-film solar cells

Yunjung Oh, Kyoohee Woo, Daehee Lee, Hongseuk Lee, Kyujin Kim, Inhyuk Kim, Zhaoyang Zhong, Sunho Jeong, Jooho Moon

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)


Recently, environmental-friendly, solution-processed, flexible Cu(In,Ga)(S,Se)2 devices have gained significant interest, primarily because the solution deposition method enables large-scale and low-cost production of photovoltaics, and a flexible substrate can be implemented on uneven surfaces in various applications. Here, we suggest a novel green-chemistry aqueous ink that is readily achievable through the incorporation of molecular precursors in an aqueous medium. A copper formate precursor was introduced to lower the fabrication temperature, provide compatibility with a polyimide plastic substrate, and allow for high photovoltaic performance. Through a comparative spectroscopic study on temperature-dependent chemical/crystal structural evolution, the chemical role of copper formate was elucidated, which led to the chalcopyrite framework that was appropriate to low-temperature annealed Cu(In,Ga)S2 absorber layers at 400 °C. This Cu(In,Ga)S2 solar cell exhibited a power conversion efficiency of 7.04% on a rigid substrate and 5.60% on a polymeric substrate. Our cell on the polymeric substrate also demonstrated both acceptable mechanical flexibility and durability throughout a repeated bending test of 200 cycles.

Original languageEnglish
Pages (from-to)17740-17747
Number of pages8
JournalACS Applied Materials and Interfaces
Issue number20
Publication statusPublished - 2014 Oct 22

Bibliographical note

Publisher Copyright:
© 2014 American Chemical Society.

All Science Journal Classification (ASJC) codes

  • General Materials Science


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