Thermal Effects on the Electronic Properties of ZnO/CdS/CIGSeS Solar Cell at the Heterojunction Interface
Sheng-Wei Hsiao1,2*, Pin-Jiun Wu2, Wu-Ching Choug1
1Institute and Department of Electrophysics, National Chiao Tung University, Hsinchu, Taiwan
2Industrial Application Group, National Synchrotron Radiation Research Center, Hsinchu, Taiwan
* presenting author:Sheng-Wei Hsiao,
The performance of solar cell will degrade under long-term sunlight exposure, one of the dominant factors is expected to be the thermal effect. Thermal energy can lead to the elemental diffusion at the heterojunction interface and the creation of the defect density in the absorber material. We investigated the thermal effect of the solar-cell device, especially on its band structure and compositional distribution, by means of hard X-ray photoemission spectroscopy (HAXPES). With probing different-thickness regions of ZnO layer, the depth-dependent photoelectron spectra reveal a decrease in the valence-band offset near the interfaces of ZnO/CdS/Cu(In,Ga)(Se,S)2 heterojuction, which can be attributed to the efficiency reduction of solar cell due to thermal effect.

Keywords: CIGSeS Solar Cells, HAXPES, Heterojunction Interface