Non‐Covalent Interaction Enhancement on Active/Interfacial Layers via Two‐Dimensional Vermiculite Doping for Efficient Organic Solar Cells

Abstract Interface modification plays an important role in improving the power conversion efficiency (PCE) of organic solar cells (OSCs). However, the low non‐covalent interaction between the cathode interface layer (CIL) and nonfullerene acceptor (NFA) directly affects the charge collection of OSCs. Here, the non‐covalent interaction between the CIL and NFA is enhanced by introducing the 2D vermiculite (VML) in the poly(9,9‐bis(3′‐(N,N‐dimethyl)‐Nethylammonium‐propyl‐2,7‐fluorene)‐alt‐2,7‐(9,9‐dioctylfluorene)) dibromide (PFN‐Br) interface layer to form an efficient electron transport channel. As a result, the electron extraction efficiency from the active layer to the CIL is increased, and the PCE of OSCs based on PBDB‐T:ITIC is boosted from 10.87% to 12.89%. In addition, the strategy of CIL doping VML is proven to be universal in different CIL materials, for which the PCE is boosted from 10.21% to 11.57% for OSCs based on PDINN and from 9.82% to 11.27% for OSCs based on PNDIT‐F3N. The results provide a viable option for designing efficient CIL for high‐performance non‐fullerene OSCs, which may promote the commercialization of OSCs.