Enhanced Efficiency and Stability of Carbon-Based Perovskite Solar Cells by Eva Interface Engineering

Nanocrystalline tin (IV) oxide (SnO 2 ) as an electron-transport layer (ETL) has unique advantages in realizing highly efficient and stable planar perovskite solar cells (PSCs), especially showing great potential in the low-temperature preparation of large-area flexible carbon-based PSCs (C-PSCs). However, the high trap density on the surface of SnO 2 tends to cause serious nonradiative recombination losses, thereby reducing photoelectric performance. In this work, an inexpensive and easily obtained polymer poly(ethylene-co-vinyl acetate) (Eva) is used as a interfacial modifier to reduce the interfacial defects and nonradiative recombination losses at the SnO 2 /perovskite interface. As a result, the crystallinity and conductivity of the perovskite layer are significantly increased, and the charge lifetime and stability are effectively improved. The Eva modified SnO 2 -based C-PSCs obtain an optimal power conversion efficiency (PCE) of 12.29%, which is 25.7% higher than that of 9.78% for the unmodified C-PSCs. Furthermore, the unencapsulated devices maintain 88.6% and 91.9% of the initial PCE over 1 month in ambient air for the unmodified and Eva-modified C-PSCs, respectively. The study provides valuable experience for the development of highly efficient and stable C-PSCs using common polymers for interface modification engineering.