Naphthodiperylenetetraimide-Based Polymer as Electron-Transporting Material for Efficient Inverted Perovskite Solar Cells

An n-type conjugated polymer NDP-V [poly(naphthodiperylenetetraimide-vinylene)] with a backbone of alternating naphthodiperylenetetraimide and vinylene is successfully used as an efficient electron-transporting layer (ETL) material in inverted planar perovskite solar cells (PSCs). It was found that device based on NDP-V exhibits a maximum power conversion efficiency (PCE) of 16.54%, whereas a maximum PCE of 15.27% is obtained based on the fullerene derivative [6,6]-phenyl-C-₆₁-butyric acid methyl ester (PC₆₁BM). The interfacial effect induced by NDP-V is studied using atomic force microscopy images, and NDP-V ensures good selective contact between the perovskite material and the metal electrode. Through steady-state and time-resolved photoluminescence, we find that NDP-V acts as an efficient electron extraction material. Additionally, compared with PC₆₁BM, NDP-V shows higher electron mobility, more hydrophobicity, and compatible energy levels with perovskite materials, thus providing higher device performance and better device stability. This work highlights the great potential of perylenediimide derivatives to replace the most popular PC₆₁BM ETL for inverted PSCs.