상세정보
학술지
Behavior of Photocarriers in the Light-Induced Metastable State in the p-n Heterojunction of a Cu(In,Ga)Se2 Solar Cell with CBD-ZnS Buffer Layer
- 발행일
- 201608
- 출처
- ACS Applied Materials & Interfaces, v.8 no.34, pp.22151-22158
- ISSN
- 1944-8244
- 출판사
- American Chemical Society(ACS)
- 협약과제
- 16PB2200, 초경량 유연 CIGS 박막 모듈 공정장비 상용화 기술개발, 정용덕
- 초록
- We fabricated Cu(In,Ga)Se2 (CIGS) solar cells with a chemical bath deposition (CBD)-ZnS buffer layer grown with varying ammonia concentrations in aqueous solution. The solar cell performance was degraded with increasing ammonia concentration, due to actively dissolved Zn atoms during CBD-ZnS precipitation. These formed interfacial defect states, such as hydroxide species in the CBD-ZnS film, and interstitial and antisite Zn defects at the p-n heterojunction. After light/UV soaking, the CIGS solar cell performance drastically improved, with a rise in fill factor. With the Zn-based buffer layer, the light soaking treatment containing blue photons induced a metastable state and enhanced the CIGS solar cell performance. To interpret this effect, we suggest a band structure model of the p-n heterojunction to explain the flow of photocarriers under white light at the initial state, and then after light/UV soaking. The determining factor is a p+ defect layer, containing an amount of deep acceptor traps, located near the CIGS surface. The p+ defect layer easily captures photoexcited electrons, and then when it becomes quasi-neutral, attracts photoexcited holes. This alters the barrier height and controls the photocurrent at the p-n junction, and fill factor values, determining the solar cell performance.
- KSP 제안 키워드
- Ammonia concentration, Aqueous solution, CIGS solar cell, Chemical bath deposition(CBD), Deep acceptor, Defect layer, Light soaking, Light-induced, P-N junction, Petri net(PN), Photoexcited electrons