Ultra-Thin Crystalline Silicon Solar Cells with Nickel Oxide Interlayer as Hole-selective Contact

Thin film crystalline silicon (c-Si) solar cells have been a potential candidate to reduce the capital expenditure associated with traditional silicon photovoltaic market. However the contact recombination becomes major concern preventing the thin-film cell performance reaching the theoretical efficiency. To reduce the effect of this problem, low-cost and silicon-compatible process is needed to suppress the contact recombination. In this work, thin film nickel oxide (NiOx) is proposed as hole-selective interlayer for c-Si solar cells, which could potentially reduce the contact recombination between p-Si/metal interfaces. The thin film NiOx layer is integrated with 2 μm thick ultra-thin c-Si solar cells by e-beam evaporation. Cell performance including open circuit voltage and efficiency are presented and discussed under different NiOx thickness and annealing condition. Experimental results showed 6mV Voc enhancement when 8nm thick NiOx is inserted when annealing condition is optimized. However the interface quality becomes another concern due to the increased series resistance associated with the extra NiOx layer.