Dual-functional carbon-doped polysilicon films for passivating contact solar cells: regulating physical contacts while promoting photoelectrical properties

Abstract

Passivating contact crystalline silicon solar cells are among the most promising industrially feasible photovoltaic (PV) technologies and require excellent physical contacts to handle device performance. Here, we report a versatile polysilicon (poly-Si) film intentionally doped with carbon (C) to suppress blistering and improve physical contacts. Our investigations of blistering mechanisms reveal that the reduced crystallization fraction of poly-Si in conjunction with the suppressed level of hydrogen release should primarily be responsible for the blistering-free appearance of the C-doped poly-Si films. Moreover, additional advantages of high-quality passivation with a high implied open-circuit voltage (iV_oc) exceeding 750 mV and an excellent optical response in the infrared band with a net current-density gain of 0.31 mA cm⁻² are endowed to the C-doped poly-Si films. Consequently, the proof-of-concept devices featuring C-doping show a champion efficiency of 24.27%, which is 1.18% higher than that of the C-free counterparts (23.09%). Also, we present a certified efficiency of 23.82%, suggesting that the C-doped poly-Si has the potential to achieve high-efficiency c-Si solar cells.