Wafer-Scale Radial Junction Solar Cells with 21.1% Efficiency Using c-Si Microwires

Abstract

Microwire (MW)-based radial junction crystalline silicon (c-Si) solar cells have great potential as an emerging energy device with an efficiency of over 20%. However, the competitive efficiency of MW-based c-Si solar cells in realizing a wafer-scale device is limiting its commercialization. In this study, the aim is to demonstrate that conventional fabrication techniques can be applied to MW-based solar cells while not only increasing the size from the lab-scale to the wafer-scale but also retaining an efficiency of >20%. Surprisingly, an improvement in open-circuit voltage and fill factor is observed with an increase in device size, due to the reduction of recombination loss at the device edge. Finally, a successful demonstration of 21.1% efficiency at 4-inch wafer-scale (25 cm(2)) in c-Si MW solar cell is observed, while an efficiency of 20.6% at a lab-scale size (1 cm(2)) is observed.