Improvement of PERC solar cell efficiency based on laser-doped selective emitter

Abstract

In recent years, high-efficiency solar cells have a strong competitiveness in the market and the p-type PERC solar cell is the mainstream product of leading cell manufacturers. To further improve the efficiency and reduce the cost, laser doping selective emitter (LDSE) has been introduced into the mass production line as a promising technology. In this work, we fabricated high efficiency PERC solar cells by using LDSE technique. Firstly, we adjusted the diffusion process and obtained the best sheet resistance (115 ± 5 Ω/sq), which resulted in an efficiency gain of 0.11%. Subsequently, the best diffusion profile of the selective emitter was obtained through optimization. With the surface concentration of about 3.0×1020 atoms/cm3 and emitter depth of 0.32 µm, the optimum photovoltaic parameter gains have been achieved, namely 0.18% for Eff, 6.7 mV for Voc and 0.25 mA/cm2 for Jsc respectively. EQE measurements show that the spectral response can be improved in the short wavelengths through introducing LDSE structure. Correscan measurements indicate that the front contact resistance of SE solar cell was slightly higher than that of reference due to the lateral transport resistance. The efficiency of LDSE solar cell can be increased further by the optimization of laser uniformity and the alignment of screen-printed finger with heavily doped region.