Macroscopic and microscopic electrical properties of Cu(In,Ga)Se<inf>2</inf> thin-film solar cells with various Ga/(In + Ga) contents
- 주제(키워드) Conductive atomic force microscopy , Cu(In , Ga)Se<inf>2</inf> , Ga/(In + Ga) , Grain boundaries
- 발행기관 Elsevier
- 발행년도 2015
- 총서유형 Journal
- URI http://www.dcollection.net/handler/ewha/000000119557
- 본문언어 영어
- Published As http://dx.doi.org/10.1016/j.cap.2015.04.036
- 저작권 이화여자대학교 논문은 저작권에 의해 보호받습니다.
초록/요약
CuIn<inf>1-x</inf>Ga<inf>x</inf>Se<inf>2</inf> (CIGS) thin-films were deposited by a three-stage co-evaporation process. We obtained an optimum value for the Ga/(In + Ga) ratio of CIGS solar cells of 0.29, which exhibits a band-gap of 1.14 eV and has the highest conversion efficiency. The Ga/(In + Ga) ratio in CIGS solar cells is one of main characteristics that can improve efficiency, but the optimum value is still uncertain. In this study, we investigated the local electrical properties, which are closely related to the device properties, of CIGS according to the Ga/(In + Ga) ratio. We measured the local current of the films using conductive atomic force microscopy. The local current indicates relatively small values for the current ratio and the average current on the film surface, which has a high shunt resistance and a low series resistance in high-efficiency CIGS thin-films. However, low efficiency CIGS exhibits the opposite electrical behavior. Thus, the macroscopic and microscopic electrical behaviors are closely correlated with the conversion efficiency and with the device factors of CIGS thin-film solar cells with a varying Ga/(In + Ga) ratio. These results suggest that the control of carrier transport over the grains will improve the conversion efficiency of CIGS thin-film solar cells. © 2015 Elsevier B.V. All rights reserved.
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