Impact of Surface Texture on Bifacial Silicon Heterojunction Solar Cell Carrier Loss

Abstract

We investigate the impact of surface texturing on current loss as a function of depth and wavelength in high efficiency bifacial silicon heterojunction solar cells operating at their maximum power output. We couple 3D ray tracing with TMM thin-film boundary conditions for optical simulations and solve Poisson’s drift-diffusion equations to calculate carrier recombination under both front and rear illumination. For front (rear) AM1.5G illumination at normal incidence, regular inverted pyramids out-perform planar surfaces and upright pyramid texture efficiencies by 17.1% rel. (17.9% rel.) and 1.4% rel. (1.0% rel.), respectively. Reduced carrier loss for inverted pyramid textures is calculated to be primarily due to a reflectivity decrease of 63% (76%) compared to planar surfaces which results in enhanced carrier-generation at depths further into the c-Si substrate. The benefit of inverted pyramidal light-trapping will be further enhanced when higher angles of incidence are considered, with angular performance particularly relevant for the rear-side.