Acid Doping of PEDOT:PSS Strengthens Interfacial Compatibility toward Efficient and Stable Perovskite Solar Cells

Poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) has been widely applied as a hole transport material in s. Although PEDOT:PSS exhibits the advantages of superior conductivity and low material cost, the corresponding devices suffer from low photovoltaic performance due to unsatisfactory interfacial properties. Here, an acid treatment strategy is developed to modify the chemical properties of PEDOT:PSS by different HX (X = Cl, Br, I) acids. We present evidence of an effective ion exchange process between HX and PEDOT:PSS and show that the anion-dependent dedoping of PEDOT:PSS leads to large variation of thin-film conductivity, film hydrophilicity, and interfacial contact between perovskite and PEDOT:PSS. PEDOT:PSS treated by HCl demonstrates optimal interfacial compatibility along with superior charge collection efficiency, which contributes to significantly enhanced device efficiency (17.63%) compared to the control device (14.56%). Moreover, the resulting unencapsulated devices based on HCl show superior long-term stability, maintaining more than 90% of their initial efficiency after 2355 h, whereas the control device only kept about 47% of original PCEs after 1120 h. This work indicates the effectiveness of acid treatment in modulating the doping properties of PEDOT:PSS and provides an efficient way to improve the interfacial performance of perovskite solar cells.