Multifunctional Polymer-Regulated SnO2Nanocrystals Enhance Interface Contact for Efficient and Stable Planar Perovskite Solar Cells

Perovskite solar cells (PSCs) have rapidly developed and achieved power conversion efficiencies of over 20% with diverse technical routes. Particularly, planar-structured PSCs can be fabricated with low-temperature (<= 150 degrees C) solution-based processes, which is energy efficient and compatible with flexible substrates. Here, the efficiency and stability of planar PSCs are enhanced by improving the interface contact between the SnO(2)electron-transport layer (ETL) and the perovskite layer. A biological polymer (heparin potassium, HP) is introduced to regulate the arrangement of SnO(2)nanocrystals, and induce vertically aligned crystal growth of perovskites on top. Correspondingly, SnO2-HP-based devices can demonstrate an average efficiency of 23.03% on rigid substrates with enhanced open-circuit voltage (V-OC) of 1.162 V and high reproducibility. Attributed to the strengthened interface binding, the devices obtain high operational stability, retaining 97% of their initial performance (power conversion efficiency, PCE > 22%) after 1000 h operation at their maximum power point under 1 sun illumination. Besides, the HP-modified SnO2ETL exhibits promising potential for application in flexible and large-area devices.