Enhancement of Light Absorption in Transparent Crystalline Silicon Solar Cells Using Light-Harvesting Film

Abstract

A light-harvesting film is considered as a means to improve the power conversion efficiency (PCE) of solar cells. However, when a light-harvesting film is applied to transparent solar cells, it is difficult to maintain the transparency of transparent solar cells due to the high haze ratio of the film (>95%). In this study, we apply a light-harvesting film onto the selective area, which is the light absorption region of the transparent c-Si solar cells. As a result, the transparent c-Si solar cells with light-harvesting film exhibited a current density (JSC) increase of 2.6 mA/cm2 compared with the transparent c-Si solar cells without a light-harvesting film. Therefore, the best device showed a PCE of 15.8% (JSC = 31.7 mA/cm2, open-circuit voltage (VOC) = 638 mV, and fill factor (FF) = 78.3%) at an average visible transmittance of 20%, while maintaining a low haze ratio (0.95%). Furthermore, the transparent c-Si solar cells with the light-harvesting film have the advantage of minimizing the PCE degradation depending on the angle of light incidence. The transparent c-Si solar cells with light-harvesting film change the JSC are under 4% for incident angles below approximately 50°, whereas that of the reference cells (conventional planar c-Si solar cells) loses over 30% in the same angle range. Hence, the proposed transparent c-Si solar cells present a unique opportunity to develop next-generation transparent solar cells, which would satisfy high efficiency and minimize PCE degradation according to the angle of light incidence.