Thin c-Si Solar Cells Based on VOx Heterojunctions With Texturized Rear Surface

Abstract

Solar cells based on thin crystalline silicon (c-Si) substrates have the potential to provide relevant efficiencies with less material. In this article, we report on the fabrication of thin solar cells starting from a 20 μ m-thick c-Si wafer. Special attention is paid to optical performance of the rear surface where we need very high internal reflection and light scattering to improve light trapping properties of the device. In this sense, we introduce a texturization of the rear surface, which is excellently passivated by aluminium oxide films. In addition, for the rear contacts we use metal-covered wide-bandgap materials to improve back reflectance with a Vanadium Oxide/c-Si heterojunction for the emitter regions while the base contacts are defined by laser processing phosphorus doped amorphous silicon carbide films. Best solar cell has a reasonable efficiency of 8.7% and, more importantly, external quantum efficiency measurements demonstrate a better performance for photons with λ > 900 nm than in the case of a flat rear surface.