Flexible and transparent thin-film light-scattering photovoltaics about fabrication and optimization for bifacial operation

Abstract

Flexible and transparent thin-film silicon solar cells were fabricated and optimized for building-integrated photovoltaics and bifacial operation. A laser lift-off method was developed to avoid thermal damage during the transfer of light-scattering structures onto colorless polyimide substrates and thus enhance front-incidence photocurrent, while a dual n-type rear window layer was introduced to reduce optical losses, facilitate electron transport for rear incidence, and thus enhance performance during bifacial operation. The introduction of the window layer increased the rear-to-front power conversion efficiency ratio to ~86%. The optimized bifacial power conversion efficiency for front and rear irradiances of 1 and 0.3 sun, respectively, equaled 6.15%, and the average transmittance within 500–800 nm equaled 36.9%. Additionally, the flexible and transparent solar cells fabricated using laser lift-off exhibited good mechanical reliability (i.e., sustained 500 cycles at a bending radius of 6 mm) and were therefore suitable for building-integrated photovoltaics.