Enhancing the adhesion between Self-Assembled Molecules and perovskite Enabled 22.6% efficiency for Flexible Solar Cells

Abstract

Flexible perovskite solar cells (F-PSCs) hold exceptional promise for portable electronics, yet emerging evidence demonstrate that their efficiency and stability are constrained by the weak adhesion between the hole transporting layer (HTL) and the perovskite. Herein, this study strengthens the interfacial adhesion by improving the film properties of HTL via optimizing the annealing temperature of different self-assemble monolayers (SAMs). It is found that an optimal annealing temperature enables to form a dense SAM with a good coverage on the flexible substrate. By using an asymmetric SAM molecule of (2-(12-phenylindolo[2,3-a] carbazol-11(12H)-yl)ethyl)phosphonic acid (CPP-2PACz), we significantly enhance the interfacial shear strength and achieve a slow-down crystallization process during the perovskite deposition, thereby resulting of perovskite films with prolonged carrier lifetime and suppressed non-radiative recombination. As a result, a champion efficiency of 22.6% has been achieved for F-PSCs, and devices retain more than 89% of the initial efficiency after 1000 h of continuous operation along with improved stability under thermal cycle aging protocol.