Enhanced performance of silicon solar cells by application of low-cost sol-gel-derived Al-rich ZnO film

Abstract

Sol-gel-derived hydrogen-annealed Al-rich zinc oxide (AZO) film has been investigated as an effective passivating layer on p-type silicon. In this paper, silicon nitride (SiNx) film is used as antireflection coating and passivating layers on a phosphorous diffused n+-front emitter, whereas sol-gel-derived hydrogen-annealed AZO film is used as a passivating and capping layer on the p-back surface of PERC (passivated emitter and rear cell with local Al back surface field) structure-based mono-crystalline (c-Si) solar cells to evaluate the potential of the AZO film. The illuminated J-V characteristics and internal quantum efficiency (IQE) of PERC and standard (conventional, full area Al back surface field) solar cells have been measured for comparison. The IQE data was used to determine the effective diffusion lengths of the solar cells, which were found to be 218.09±4.36 and 571.13±11.42μm for standard and PERC solar cells, respectively. The effective back surface recombination velocity of the PERC solar cell was found to be ~67cm/s with a metal coverage area of 12%, which is lower than the back surface recombination velocity (~451cm/s) of the standard solar cell. The achieved conversion efficiencies of the standard and PERC solar cells were 14.31±0.08% and 15.16±0.09%, respectively. © 2013 Elsevier Ltd.