Simulated multi-crystalline silicon solar cells with aluminum back surface field

Abstract

In photovoltaic solar cells manufacturing, we are confronted to the perpetual challenge for conversion efficiency enhancing. We propose in this work to quantify the back surface field aluminium (Al-BSF) rear contact effect deposited by screen printing metallization. Al-BSF numerical simulation has been performed by the use of softwares dedicated to photovoltaic like PC1D, SCAPS 2.7 and AFORS-HET. In this work, a SiNx/Si(n+)/ Si(p)/Si(p+) structure is studied. This means that we have a classical junction np passivated at the front face with SiNx anti-reflective coating (ARC) and at the rear face a screen printed Aluminum contact. The back Al-BSF, must to be thick (no least 10µm) and highly p-doped (holes concentration between 1018 and 1019 cm-3) in order to reduce effective rear recombination velocity, yielding to an enhancement of the Al layer performance. Were inserted in the software parameters data: the lifetime measured for the inner bulk (Tn=30 µs and Tp=90 µs) with Al diffusion (10.8 µm deep). For emitter doping equals to 1.5*1020 cm-3, front surface recombination velocity Sf=8600 cm/s and the effective minority diffusion length Leff=227 µm. After simulation of the input parameters, an efficiency of 18.0% is obtained by PC1D, in good accordance with the results presented in the literature. While the obtained efficiencies results with AFORS-HET and SCAPS 2.7 are 17.15% and 18.73% respectively. A rapprochement occurs between PC1D and SCAPS quantum efficiency curves with begin values ~ 70% QE while AFORS-HET is so far with ~ 34% QE