Tailored Band Structure of Cu(In,Ga)Se-2 Thin-Film Heterojunction Solar Cells: Depth Profiling of Defects and the Work Function
- 주제(키워드) Cu(In , Ga)Se-2 , thin film , solar cells , bandgap grading , conduction band offset
- 주제(기타) Nanoscience & Nanotechnology; Materials Science, Multidisciplinary
- 설명문(일반) [Park, Ha Kyung; Jo, William] Ewha Womans Univ, Dept Phys, Seoul 03760, South Korea; [Cho, Yunae; Jo, William] Ewha Womans Univ, New & Renewable Energy Res Ctr, Seoul 03760, South Korea; [Kim, Kihwan; Jeong, Inyoung; Gwak, Jihye] Korea Inst Energy Res KIER, Photovolta Lab, Daejeon 34129, South Korea; [Yun, Jae Ho] Korea Inst Energy Technol, Dept Energy Engn, Naju 58330, South Korea
- 등재 SCIE, SCOPUS
- 발행기관 AMER CHEMICAL SOC
- 발행년도 2022
- 총서유형 Journal
- URI http://www.dcollection.net/handler/ewha/000000202926
- 본문언어 영어
- Published As https://doi.org/10.1021/acsami.2c0716634697
- PubMed https://pubmed.ncbi.nlm.nih.gov/35856522
초록/요약
An efficient carrier transport is essential for enhancing the performance of thin-film solar cells, in particular Cu(In,Ga)Se2 (CIGS) solar cells, because of their great sensitivities to not only the interface but also the film bulk. Conventional methods to investigate the outcoming carriers and their transport properties measure the current and voltage either under illumination or dark conditions. However, the evaluation of current and voltage changes along the cross-section of the devices presents several limitations. To mitigate this shortcoming, we prepared gently etched devices and analyzed their properties using micro-Raman scattering spectroscopy, Kelvin probe force microscopy, and photoluminescence measurements. The atomic distributions and microstructures of the devices were investigated, and the defect densities in the device bulk were determined via admittance spectroscopy. The effects of Ga grading on the charge transport at the CIGS-CdS interface were categorized into various types of band offsets, which were directly confirmed by our experiments. The results indicated that reducing open-circuit voltage loss is crucial for obtaining a higher power conversion efficiency. Although the large Ga grading in the CIGS absorber induced higher defect levels, it effectuated a smaller open-circuit voltage loss because of carrier transport enhancement at the absorber-buffer interface, resulting from the optimized conduction band offsets.
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