Interface engineering of perovskite solar cells with PEO for improved performance

Interface engineering is an important and efficient way to further improve the conversion efficiency of perovskite solar cells. In this study, we report the modification of the electron transport layer (ETL) using a thin layer of PEO. Characterizations showed that PEO was uniformly coated on top of the original TiOx ETL, without resulting in an evident change of the surface morphology, hydrophilic ability or transparency. With the interface dipole formed at the interface, the work function of the ETL greatly decreased. Compared with devices with TiOx only, devices based on the modified ETL gave a nearly 15% enhancement to the overall conversion efficiency, with both V-oc and J(sc) improved. Further studies showed that the improved performance could mainly be attributed to the better retardation of back recombination and the enhanced electron collection efficiency bymeans of the PEO thin layer modification.