Interface Modification of Tin Oxide Electron‐Transport Layer for the Efficiency and Stability Enhancement of Organic Solar Cells

Abstract

AbstractA small molecular phenanthroline derivative Phen‐NaDPO (3‐[6‐(diphenylphosphinyl)‐2‐naphthalenyl]‐1,10‐Phenanthroline) to modify tin oxide (SnO2) electron‐transport layer (ETL) in organic solar cells is employed. Quantum chemistry calculations and experimental results show that Phen‐NaDPO can interact with SnO2, thereby effectively passivating the surface defects, reducing the work function and improving the electrical conductivity of SnO2, leading to more efficient electron extraction and transport in the organic solar cells (OSCs). Moreover, upon the Phen‐NaDPO modification, the decreased surface energy of SnO2 ETL accounts for enhanced exciton dissociation and charge transport, due to the more ordered molecular organizations of the active layers. Consequently, the inverted OSCs involving Phen‐NaDPO/SnO2 ETLs exhibit an enhanced power conversion efficiency of 17.06% (PM6:Y6) and 18.31% (PM6:L8‐BO), which is the highest efficiency for SnO2 ETL‐based binary solar cells to date. Furthermore, the devices based on Phen‐NaDPO/SnO2 ETL show better device stability (storage stability, photostability and humid stability), with T80 exceeding 200 h encapsulated under light irradiation and 400 h without encapsulation in high‐humidity ambient condition. These results demonstrate that the modification of SnO2 using wide‐band highly stable conjugated small molecules is very promising for simultaneously improve the efficiencies and device stability of OSCs.