[19p-PA5-1~14] 16.3 Bulk, thin-film and other silicon-based solar cells

▲ [19p-PA5-1] Reduced recombination losses for PERC cell using a selective emitter structure formed by screen-printed resist masking combined with etch-back process

〇(P)Supawan Joonwichien¹, Yasuhiro Kida¹, Masaaki Moriya¹, Satoshi Utsunomiya¹, Katsuhiko Shirasawa¹, Hidetaka Takato¹ (1.AIST)

Keywords:Passivated emitter and rear cell (PERC), Selective emitter, Wet chemical etch-back process

We present the improvement of the p-type passivated emitter and rear cell (PERC) with a selective emitter (SE) structure using screen-printed resist masking combined with wet chemical etch-back process. The concept of an SE structure is based on removal of the highly doped layers (n⁺⁺) in the areas not intended for metallization. For p-type solar cells, the lightly doped emitter areas (n⁺) obtained by the above mentioned process lead to a reduced Auger recombination and Shockley-Read-Hall (SRH) recombination, thereby improving the performance of PERCs. An n⁺ emitter by etch-back process showing high sheet resistance (R_sheet) ensures a better blue response, resulting in high internal quantum efficiency. As a result, the SE structure had a considerable impact on the parameters of the PERCs, showing an increase in the open-circuit voltage (V_oc), but a decrease in the short-circuit current density (J_sc) and fill factor (FF) compared with homogeneous emitter (HE) cells. In addition, the experimental results of PERCs have been modeled using PC1D simulating program to calculate and compare the influence of SE structure, initial R_sheet of n⁺⁺, and n⁺/n⁺⁺ ratio on the V_oc. The diminished FF for SE structure was simulated by Two-diode model. These results suggest that the improvement of the emitter by an SE structure is essential for improving conversion efficiency of industrial-sized PERC solar cells.