Ray Tracing of Light Trapping Schemes in Thin Crystalline Silicon for Photovoltaics

Abstract

Thin crystalline silicon (c-Si) suffers from poor light absorption which hinders generation of high photocurrent in photovoltaic (PV) devices. To overcome this issue, efficient light trapping (LT) schemes need to be incorporated into the thin c-Si absorber. This paper presents ray tracing of LT schemes in thin c-Si to enhance broadband light absorption within 300-1200 nm wavelength region. For the ray tracing, mono c-Si wafer with 100 μm thickness is investigated and solar spectrum (AM1.5G) at normal incidence is used. Front and rear pyramid textures, silicon nitride (SiNx) anti-reflective coating (ARC) and back surface reflector (BSR) are the LT schemes being studied in this work. With incremental LT schemes, optical properties of the thin c-Si are analyzed. From the absorption curve, maximum potential photocurrent density (Jmax) is calculated, assuming unity carrier collection. The c-Si reference (without LT) exhibits Jmax of 24.93 mA/cm2. With incorporation of incremental LT schemes into the thin c-Si, the Jmax increases, owing to enhanced light coupling and light scattering in the c-Si absorber. The Jmax up to 42.12 mA/cm2 is achieved when all the LT schemes are incorporated into the thin c-Si absorber. This represents 69% enhancement when compared to the Jmax of the c-Si reference.