Optimization of p-a-SiC:H/p-nc-SiC:H double layer structure for a high efficiency a-Si:H based solar cell

We optimized a p-a-SiC:H/p-nc-SiC:H double p-layer structure to achieve high performances for a-Si:H based solar cells. We could reduce remarkably the recombination in the buffer layer and at the p/buffer/i interfaces by employing a lightly boron-doped (∼1000 ppm) p-nc-SiC:H buffer material with a high conductivity, low defect density, and low absorption, resulting in a good buffering effect of improving V_oc and J_sc values. As a result, we could achieve the 11.2 % initial-efficiency for a-Si:H solar cell and 10.4 % for a-Si:H multilayer solar cell without using any back reflector. Since the a-Si:H multilayer solar cell shows the excellent light-soaked behavior, a 8.98 % stabilized-efficiency (degradation ratio: 13.4 %) is obtained.