Development of High Density Nano-protrusions onto CuInS₂ , Cu(In,Ga)S₂, CuInSe₂, and Cu(In,Ga)Se₂ with Distinction Antireflection Properties
Yu-Ting Yen1*, Yi-Chung Wang1, Yu-Ze Chen1, Hung-Wei Tsai1, Cheng-Hung Hsu1, Shih-Ming Lin1, Chih-Chung Lai1, Yu-Lun Chueh1
1Department of Materials Science and Engineering, National Tsing Hua University, Hsinchu City, Taiwan
* presenting author:Yu-Ting Yen,
Copper indium (gallium) diselenide (CI(G)Se₂) and its related sulfide (copper indium (gallium) disulfides, CI(G)S₂) are promising chalcopyrite thin film solar cell absorber materials due to versatile bandgap tailoring properties. 20.8 % photo-electric conversion efficiency has been demonstrated by lab-scale CIGSe2 thin film devices, which beats all the other thin film PV competitors such as amorphous-silicon and cadmium telluride. However, the highly cost of indium and gallium elements hinder developments of chalcopyrite thin film PV towards grid-parity. In order to achieve the goal for commercialization of low cost chalcopyrite thin film PV, researchers are devoted to reduce the raw materials usage and improve the absorption capabilities of the intrinsic chalcopyrite materials. In this work, we propose a facile approach to create high density, high throughput, and outstanding anti-reflectance nano-protrusions onto four kinds of chalcopyrite thin films (CuInS₂, Cu(In,Ga)S₂, CuInSe₂, and Cu(In,Ga)Se₂). The length and orientation can be controlled, depending on argon ion incident energy and angles. Remarkable high density (10¹⁰ nano-protrutions /cm²) can be created on four kinds of chalcopyrite thin films under low energy argon ion irradiation (below 1 kV). Moreover, distinction anti-reflection properties can be observed through four kinds of chalcopyrite nano-protrutions, UV-Vis spectrophotometer evidenced chalcopyrites nano-protrutions behaving outstanding anti-reflection through 350 to 2000 nm compared to the pristine chalcopyrites. Consequently, this approach enable high density, high absorption of nanoprotrutions created onto four kinds of chalcopyrite materials by low energy ion irradiations. Moreover, a ~4 inch size CIGSe₂ nano-protrutions was demonstrated, which can be beneficial for chalcopyrite PV developments in the future.

Keywords: Nanostructure, Antireflection, Cu(In,Ga)(S,Se)2