Down-converting ultraviolet light using a conductive passivator to enhance the efficiency and stability of perovskite solar cells

The significant progress of perovskite solar cells (PSCs) in the past decade has shown enormous potential for industrialization; however, several critical issues such as long-term stability and potential lead leakage still need to be addressed. It is a practical challenge to overcome these issues through one approach. Herein, we introduce an ultraviolet absorbent and conductive passivation agent 4,4′-diaminostilbene-2,2′-disulfonic acid (DSDA) into SnO₂ to down-convert ultraviolet light into visible light and enhance the conductivity of SnO₂, thereby improving the light-stability and performance of PSCs. The amphoteric DSDA molecule with four functional groups can also passivate defects on the surface of SnO₂ films, affect the crystal growth of the perovskite layer, and provide in situ protection against lead leakage. Our results show that the power conversion efficiency (PCE) of the PSCs increases evidently from 22.95% to 25.09% owing to the simultaneous enhancement of the photoelectric properties of SnO₂ films and the critical SnO₂/perovskite interfaces by adding DSDA into SnO₂ films. Importantly, the DSDA-optimized PSCs without encapsulation exhibited enhanced operational and UV-light stability, as well as in situ fixation of leaked lead ions. This simultaneous enhancement of both optical and electrical properties of functional layers via adding a multifunctional organic compound provides an efficient strategy to effectively improve the efficiency and long-term stability of PSCs.