Interfacial and Permeating Modification Effect of n-type Non-fullerene Acceptors toward High-Performance Perovskite...

Interface passivation in the electron transport layer (ETL) has emerged as a very important and challenging topic for the improvement of stability and efficiency of perovskite solar cells (PSCs). Here, we introduce the n-type small organic molecule Y6 that acts as an effective ETL modifier through surface engineering. As a result, the simple PCBM + Y6 ETL led to significantly stronger light absorption, higher electron extraction ability and transportability, and reduced recombination loss in regular MAPbI₃ PSCs. The power conversion efficiency can be significantly increased from 17.39 to 20.02% in inverted p-i-n MAPbI₃ PSCs without additional alternation, with an increment of over 15%, along with higher open-circuit voltage and short-circuit current. What is more, the devices with the Y6-modified ETL also exhibited better long-term stability compared to the control devices. This indicates the feasibility of enhancing absorption over a wider light spectrum in a single-junction cell and gaining a comprehensive understanding of interface engineering between the ETL and perovskite layer.