PROGRESS IN CONTACTING a-Si:H/c-Si HETEROJUNCTION SOLAR CELLS AND ITS APPLICATION TO INTERDIGITATED BACK CONTACT STRUCTURE

摘要

This work presents our progress in designing the rear emitter of a-Si:H/c-Si (n) heterojunctions solar cells (Si-HJ). We study the emitter saturation current density (J_(0e)) of p-type a-Si:H layers and show that it greatly depends on the layer thickness and conductivity. Different p-type a-Si:H emitters are tested experimentally on Rear Emitter (RE) as well as Interdigitated Back Contact (IBC) Si-HJ devices. A low conductivity (1.4×10~(-6) S·cm~(-1)) layer allows the better Voc values about 650 mV but causes resistive losses on both types of solar cells. For the IBC devices, a low emitter contact fraction induces not only fill factor (FF) losses but also a decrease of the short circuit current (J_(sc)) value. By optimizing the rear side geometry an efficiency of 12.7% is achieved for the Si-HJ IBC structure on 25 cm~2 n-type substrate.