Multi-layered hydrogenated p-type microcrystalline silicon windows for a-Si: H thin film solar cells on opaque substrates

The effects of multi-layered p-type microcrystalline (μc-) Si:H windows on the performance of substrate-type amorphous Si:H thin film solar cells on opaque substrates were investigated. The results were well explained in terms of H₂-plasma-induced damage (HPID) at the p/i-interface and the near-interface region of the light-absorbing layer. The μc-Si:H was deposited using plasma enhanced chemical vapor deposition in a H₂-rich atmosphere. A high microcrystalline volume fraction was obtained with a high H₂ dilution ratio, which can cause considerable HPID. Cell efficiency was enhanced with a multi-layered p-type μc-Si:H composed of films with low and high crystalline volume fraction, compared to cells with single-layered μc-Si:H. In the multi-layered p-type μc-Si:H, the low crystalline film was placed on an i-Si:H layer to reduce HPID. The present work demonstrated that HPID was reduced at the p/i-interface and the near-interface region of the light-absorbing layer, and that the quality of the p-type μc-Si:H needs to be a significant consideration to achieve high efficiency.