Hexagonal 2D covalent organic frameworks from nonpolar and symmetric electron-accepting substituents for electron transport layers in near-infrared PeLEDs

Abstract

We conducted high-throughput calculations on the structure library of two-dimensional covalent organic frameworks (2D COFs), with the aim of finding new candidate materials as electron transport layers (ETLs) for the high-performance perovskite light-emitting diodes (PeLEDs). Starting with nearly 400 unique 2D COFs with hexagonal (hcb) topology, 23 candidates for β-ketoenamine linked 2D COFs composed of 1,3,5-triformylphloroglucinol (Tp) and linear diamines are identified by band structures. Interestingly, 2 β-ketoenamine linked 2D Tp-DAAQ and 2D Tp-DABDA with electron-accepting substituents, are the most promising candidates due to the optimal band edge and effective mass. Further, the nonpolarity of the Tp-DAAQ molecule makes it a more favorable choice for the ETL, as confirmed by nonadiabatic molecular dynamics that 2D Tp-DAAQ with anthraquinone diamine linker has a longer e–h nonradiative recombination time. This work provides a paradigm for the design of high-performance ETLs.