LAUSR

Inverted perovskite solar cells (PSCs) have gained rapid progress and increasing research interest in recent years. The poly (triarylamine) (PTAA) is the most frequently used semiconductor in the hole-transporting layer (HTL) in inverted PSCs for its favorable highest occupied molecular orbital energy level (-5.2 eV), excellent carrier mobility, and low-temperature solution processability. However, its intrinsic hydrophobic property hinders the growth of high-quality perovskite on the PTAA film, which is one of the main obstacles that limits the further development of inverted PSCs. Herein, a donor-acceptor-donor type organic molecule, 4,4',4″-(1-hexyl-1H-dithieno [3',2':3,4; 2″,3″:5,6] benzo[1,2-d] imidazole-2,5,8-triyl) tris (N,N-bis(4-methoxyphenyl) aniline) (denoted as M2), is employed to modify the surface of PTAA. The PTAA/M2 composite hole transport layer facilitates the growth of perovskite films due to ameliorated hydrophobic property of PTAA. PTAA/M2 also exhibits enhanced hole mobility and conductivity than pristine PTAA. With enhanced crystallinity and hole extraction ability, using PTAA/M2 instead of pure PTAA as HTL, the power-conversion efficiency of inverted PSC increases from 18.67% to 20.23%. Furthermore, its operational stability is also enhanced. Our methodology carves out a novel path for addressing the hydrophobic issue of PTAA and improving the efficiency and photostability of inverted PSCs.