플렉서블 실리콘 박막 태양전지용 ZnO:Al/Ag 후면반사막의 표면형상에 따른 광산란 특성 변화

서지정보

ㆍ발행기관 : 한국재료학회 ㆍ수록지정보 : 한국재료학회지 / 20권 / 10호
ㆍ저자명 : 백상훈, 이정철, 박상현, 송진수, 윤경훈, 왕진석, 이희덕, 조준식

영어 초록

Changes in surface morphology and roughness of dc sputtered ZnO:Al/Ag back reflectors by varying the deposition temperature and their influence on the performance of flexible silicon thin film solar cells were systematically investigated. By increasing the deposition temperature from 25˚C to 500˚C, the grain size of Ag thin films increased from 100 nm to 1000 nm and the grain size distribution became irregular, which resulted in an increment of surface roughness from 6.6 nm to 46.6 nm. Even after the 100 nm thick ZnO:Al film deposition, the surface morphology and roughness of the ZnO:Al/Ag double structured back reflectors were the same as those of the Ag layers, meaning that the ZnO:Al films were deposited conformally on the Ag films without unnecessary changes in the surfacefeatures. The diffused reflectance of the back reflectors improved significantly with the increasing grain size and surface roughness of the Ag films, and in particular, an enhanced diffused reflectance in the long wavelength over 800 nm was observed in the Ag back reflectors deposited at 500˚C, which had an irregular grain size distribution of 200-1000 nm and large surface roughness. The improved light scattering properties on the rough ZnO:Al/Ag back reflector surfaces led to an increase of light trapping in the solar cells, and this resulted in a noticeable improvement in the Jsc values from 9.94 mA/cm2 for the flat Ag back reflector at 25˚C to 13.36 mA/cm2 for the rough one at 500˚C. A conversion efficiency of 7.60% (Voc = 0.93, Jsc = 13.36 mA/cm2, FF = 61%) was achieved in the flexible silicon thin film solar cells at this moment.

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