Multifunctional Polymer Framework Modified SnO₂ Enabling a Photostable α-FAPbI₃ Perovskite Solar Cell with Efficiency Exceeding 23%

Poly(ethylene glycol) diacrylate (PEGDA) is introduced into the SnO2 dispersion as the polymer framework to hinder the agglomeration. The PEGDA-modified SnO2 acted as the electron transport layer (ETL) in n-i-p structured perovskite solar cells (pero-SCs). It is demonstrated that the PEGDA plays multifunctional roles in the enhancement of photovoltaic performance and stability against illumination and humility. First, the PEGDA-modified SnO2 ETL is more uniform, and its energy level matched well with the perovskite, which could facilitate the carrier transport and reduce the energy loss. Second, PEGDA could passivate the defects at the interface between perovskite and ETL. Eventually, a power conversion efficiency (PCE) of 23.31% is achieved for the α-FAPbI3 based pero-SCs. Most importantly, the unencapsulated devices maintained more than 90% of the initial PCE after 850 h continuous illumination (100 mW/cm2). This study could provide insight for the low-cost, facile, and efficient interface modification for the pero-SCs.