High-efficiency CNT-Si solar cells based on a collaborative system enabled by oxide penetration

Carbon nanotube-silicon (CNT-Si) solar cells represent one of the alternative photovoltaic techniques with potential for low cost and high efficiency. Here, we report a method to improve solar cell performance by depositing conventional transitional metal oxides such as WO 3 and establishing a collaborative system, in which CNTs are well-embedded within the WO 3 layer and both of them are in close contact to Si substrate. This unique collaborative system optimizes the overall energy conversion process including the light absorption (antireflection by WO 3 ), carrier separation (forming quasi p-n junction) and charge collection (CNT conductive network throughout the oxide layer). Combining with our previous TiO 2 -coating and HNO 3 -doping techniques, a solar cell efficiency of >18% at an active area of 0.09 cm 2 (air mass 1.5, 100 mW/cm 2 ) was achieved. The oxide-enhanced CNT-Si solar cells which integrate the advantages of traditional semiconductors and novel nanostructures represent a promising route toward next-generation high-performance silicon-based photovoltaics.