Enhancing the Efficiency and Durability of Perovskite Solar Cells by Donor-Acceptor Covalent Organic Framework with Thiazolo[5,4-d] thiazole Unit

Donor-Acceptor (D-A) alignment is considered a productive strategy to improve the charge separa-tion efficiency of covalent organic frameworks (COFs) and enhance the charge-transfer yield (CTY) of COFs. Moreover, organic molecules containing heteroatoms can produce coordination interaction with PbI2 of perovskite precursor to affect the crystallization process, thereby impeding the decomposition and improving the stability of perovskite materials. Herein, a thiazolo[5,4-d]thia-zole (TZ)-based D-A type COFTPDA-TZDA was designed and synthesized from N,N,N ',N '-tetrakis (4-aminophenyl)-1,4-benzenediamine (TPDA) and 4,4 '-(thiazolo[5,4-d]thiazole-2,5-diyl)dibenzalde-hyde (TZDA). Upon incorporation into the FAPbI3 layer, COFTPDA-TZDA not only restrained the perov-skite defects and enhanced the grain size of perov-skite films through the coordination effect of the N atoms of TZDA but also ameliorated the charge transport within the perovskite film, which was the benefit of the D-A structure of COFTPDA-TZDA. As a result, incorporation of COFTPDA-TZDA into the perov-skite solar cells (PSCs) led to a remarkable power conversion efficiency (PCE) of up to 23.51%. Further-more, even after being stored in high relative humid-ity (RH approximate to 60%) for 480 h, these PSCs maintained over 90.55% of their original PCE. This work sets the foundation for the development of highly efficient and stable PSCs by utilizing TZ-based D-A type COFs.