Development of high efficiency rear-emitter n-type silicon heterojunction solar cells

Amorphous silicon/crystalline silicon heterojunction solar cells have high open-circuit voltages (Voc) due to excellent passivation on n-type wafer surfaces by thin intrinsic amorphous silicon layers. In this paper, we focus on development of high efficiency rear-emitter heterojunction solar cells using n-type silicon wafers, mainly in three aspects: (1) intrinsic amorphous silicon layer optimization for obtaining superior wafer surface passivation, (2) n-type amorphous silicon film optimization, as a window layer, for high Voc and fill factor (FF), and (3) transparent conductive oxide (TCO) layer development for high transmittance and well balancing between short-circuit current density (Jsc) and FF. After process optimization, we attained 21.7% certified efficiency on a 152.3cm² n-type silicon wafer with Jsc of 38.25mA/cm² and Voc of 721mV.