Efficiency enhancement of bifacial PERC solar cells with laser‐doped selective emitter and double‐screen‐printed Al grid

We report that the application of a laser‐doped selective emitter (SE) can improve the trade‐off between the recombination in the emitter and the Ag‐Si specific contact resistance and that a double‐screen‐printed rear aluminum grid can decrease the series resistance in the industrial bifacial passivated emitter and rear cell (PERC). Our results reveal that a front‐side efficiency of 21.9% can be achieved in the PERC (SE)+ solar cell by using low surface‐recombination Al 2 O 3 /SiN x films as passivation layers, low‐recombination emitter, and low resistive Ag‐Si contact with an optimized sheet resistance of the lightly doped area of SE with 125Ω/sq and sheet resistance of the highly doped area of SE with 70 Ω/sq. The highest front‐side efficiency of 22.0%, with open‐circuit voltage of 680 mV, short‐circuit current density of 40.1 mA/cm 2 , and fill factors of 80.8%, is obtained by using double‐screen‐printed rear Al grid process, which is 0.1% higher than the best PERC (SE)+ solar cell. The rear‐side double‐layer antireflection coating consists of 50 nm SiN x :H (n = 2.1) and 10 nm SiN x :H (n = 2.37), which enables a large bifacial gain with the output power density P MPP of 25.5 mW/cm 2 in the PERC (SE)+ solar cell by using double‐screen‐printed rear Al grid process when rear‐side illumination intensity E rear  = 0.25 suns.