BIFACIAL CIGS THIN FILM SOLAR CELLS

摘要

Bifacial CIGS solar cell with a ZnO:Al/ZnO/CdS/CIGS/ITO/SLG structure using ITO back contacts have been fabricated. The dependence of cell performance on thickness and Ga content has been investigated. The QE at short wavelengths for rear-side illumination has been recognized one of the key issues to achieve high efficiency bifacial CIGS devices. The cell performance of the CIGS device was improved by optimizing thickness and Ga content in the CIGS layer. EBIC analysis revealed that the space-charge region shifted towards the CdS/CIGS interface and narrowed as the Ga content increased, agreeing well with the spectral response curves. A best bifacial cell showed total area efficiencies of 12.6 % and 7.4 % for front and rear side illumination, respectively. A maximum apparent cell efficiency (defined using the total output power) of 20.0 % was achieved when both sides of the bifacial device are illuminated simultaneously.