TCO/(N-TYPE)A-SI:H/(P-TYPE)C-SIHETEROJUNCTION SOLAR CELLS WITH HIGH OPEN CIRCUIT VOLTAGE

摘要

This paper analyzes a front side a-Si:H/c-Si passivation scheme and emitter for p-type crystalline silicon solar cells. The scheme consists of a stack of intrinsic and highly n-type doped a-Si:H. We characterize the quality of this passivation scheme by measuring the effective lifetime of symmetric a-Si:H coated c-Si wafers. Subsequently, we fabricate solar cells and apply the a-Si:H layer stack as an emitter. Using float-zone Wafers equipped with flat a-Si:H/ZnO:Al emitters and back contacts having a thermal oxide passivation and aluminum point contacts, we achieve open circuit voltages of V_(oc) = 683 mV and efficiencies up to η = 17.4 %. The efficiency of these cells is limited by a low short circuit current due to the non-textured front side. Using the same back contact and textured wafers with a-Si:H/ITO-emitters, we reach V_(oc) = 660 mV and η = 18.5 %, so far limited by a relatively low fill factor of FF= 74.3 %.