Improving the efficiency and stability of inverted perovskite solar cells with dopamine-copolymerized PEDOT:PSS as a hole extraction layer

Despite the superior photovoltaic efficiencies of perovskite solar cells (PSCs), the relatively low long-term stability of the perovskite layer against ambient moisture is a tremendous obstacle for the practical applications of PSCs. Poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS) suffers from the limitations of high acidity and low work function. Herein, for the first time, dopamine was doped to modify PEDOT: PSS to develop a new hole extract material (HEM), DA-PEDOT:PSS; moreover, since dopamine is basic in nature, it reduced the acidity of PEDOT: PSS, thereby improving the device stability of planar heterojunction PSCs. The new HEM exhibited extremely low acidity and showed highly enhanced device durability. Moreover, when compared with that of PEDOT: PSS, the work function of DA-PEDOT: PSS was higher and made the DA-PEDOT: PSS-based PSC achieve a higher power conversion efficiency (PCE) of 16.4% due to the obvious enhancement of V-oc, and DA-PEDOT: PSS showed significantly enhanced long-term device stability as compared to PEDOT: PSS under unencapsulated condition. Intriguingly, after 28 days of aging, the PCE and J(sc) of DA-PEDOT: PSS still remained 85.4% and 89.2%, respectively, as compared to those of PEDOT: PSS (PCE of 60.4% and J(sc) of 59.3%). Dopamine-copolymerized PEDOT: PSS showed great advantage over PEDOT: PSS for the enhancement of device durability.