Quantum-well passivating contact at polysilicon/crystalline silicon interface for crystalline silicon solar cells

Abstract

Polysilicon/crystalline silicon (poly-Si/c-Si) passivating contact is attracting attention as a promising passivation technology for c-Si solar cells. Recently, we have proposed a quantum-well passivating contact (QWPC) that uses a quantum-well at the poly-Si/c-Si interface to suppress recombination, such as Auger and/or Shockley-Read-Hall recombination, due to deep dopant-diffusion problems from poly-Si into the c-Si absorber and, as a result, promote the passivation quality. Herein, we demonstrate the effectiveness of the QWPC in a large area (272.13 cm2) of c-Si photovoltaic devices. A reference device, featuring a front boron diffusion emitter and normal rear poly-Si/c-Si passivating contact without QWPC, achieves a certified 22.99% conversion efficiency. The QWPC significantly reduces recombination losses within the device, as demonstrated by bias external quantum efficiency and dark I-V characteristics. The QWPC improves the open-circuit voltage (Voc) by 20 mV. An antireflection magnesium fluoride coating applied at the front along with the QWPC improves the short-circuit current density by 1.27 mA/cm2. The QWPC device achieves a conversion efficiency of 23.91%. The QWPC demonstrates an innovative passivating contact for promoting c-Si solar cell performance.