High Open-Circuit Voltage and Its Low Temperature Coefficient in Crystalline Germanium Solar Cells Using a Heterojunction Structure with a Hydrogenated Amorphous Silicon Thin Layer

摘要

We developed hydrogenated amorphous silicon (a-Si:H)/crystalline germanium (c-Ge) heterojunction solar cells for the first time to improve the open-circuit voltage (V_(oc)) at high temperatures. By using the optimum i layer thickness of 13nm, we obtained V_(oc) of 0.266 V, that is comparable to the highest V_(oc) ever reported under 1 sun illumination. The temperature dependence of the a-Si:H/c-Ge heterojunction solar cell reveals a better temperature coefficient (-0.66%/℃) of V_(oc) than conventional homojunction solar cells. The high V_(oc) and low temperature coefficient are attributed to the benefit of the heterojunction and the excellent surface passivation capability of a-Si:H.