Synchronously modulating the strength of chemical and electric field-induced passivation for robust and efficient perovskite photovoltaics

Abstract

One of the primary challenges of perovskite solar cells (PSCs) towards commercialization is to simultaneously achieve sufficient stability and high power conversion efficiency (PCE). Here, we propose a synchronous modulation of the strength of chemical and electric field-induced passivation strategies to comprehensively heal the imperfect characteristics of perovskite. Two nitrogen-rich small molecules with asymmetric geometry, namely AS-BP and AS-AZO, were designed and synthesized. The target molecule AS-AZO, featuring the most Lewis-base active sites and the largest dipole moment, can effectively passivate defects of perovskite and improve the built-in potential of derived PSCs. Moreover, the most flexible molecular structure of AS-AZO ensures that it acts as a molecular creeper towards the perovskite grain, not only largely relieving the residual strain, but also reinforcing the overall passivation capability. The abovementioned effects of AS-AZO largely stabilize the perovskite and optimize the charge carrier dynamics of derived PSCs, leading to robust stability against humidity, thermal stress and light soaking along with a promising PCE of 25.12% versus that of the control one (21.82%). Our work offers valuable insights for designing molecules featuring sufficient chemical and electric field effects for synchronous passivation capability for assembling robust and efficient PSCs.