In Cu 2 ZnSn(S, Se) 4 (CZTSSe) solar cells, the conventional magnetron‐sputtered ZnO (ZnO‐SP) suffers from high cost, low efficiency, and interface damage. This study systematically compares sol–gel ZnO (ZnO‐SG) and 18C6 crown ether‐modified sol–gel ZnO (ZnO‐SG‐18C6) as interfacial layers. X‐ray diffraction (XRD), scanning electron microscope (SEM), AFM, and X‐ray photoelectron spectroscopy (XPS) show ZnO‐SP has a uniform hexagonal wurtzite structure, whereas ZnO‐SG displays an amorphous fibrous morphology with bright/dark striations. Both exhibit similar UV absorption peaks, but ZnO‐SG shows broader absorption and double‐exponential decay. Density–voltage ( J – V ) tests reveal that ZnO‐SG‐18C6 increases PCE from 8.5% to 10.6%, surpassing the 9.5% achieved with ZnO‐SP. Electrochemical impedance spectroscopy (EIS) analysis shows that the ZnO‐SG‐18C6 layer reduces carrier recombination, with the charge transfer resistance ( R ct ) increasing by 30%. Transient photocurrent measurements further reveal that it enhances the photocurrent response, achieving a 1.8‐fold increase in the peak, which rises to four times under a 70% high duty cycle.This work demonstrates ZnO‐SG‐18C6 as a low‐cost, high‐efficiency alternative to ZnO‐SP in CZTSSe solar cells.
Zhou et al. (Tue,) studied this question.