Revelation of the photoexcitation mechanism of COF-DFB materials based on first principles

Abstract

A two-dimensional covalent organic framework (COF) material successfully prepared in the experiment exhibits good light absorption performance, but its internal mechanism is still unclear. A deep understanding of the excitation mechanism of COF materials is of great significance for the preparation and modification of two-dimensional materials. First, the geometric structure of COF-DFB was determined using first-principles and quantum chemical methods, revealing a pore size of 11.62 Å. Secondly, the electron–hole distribution of each excited state of COF-DFB with an oscillator strength greater than 0.1 was further analyzed. It was found that in most excited states of COF-DFB, the electrons are mainly distributed on the TMBP monomer, while the holes are concentrated between TMBP (2,2′,6,6′-tetramethyl-4,4′-bipyridine) and DFB (1,4-diformylbenzene). Finally, the UV-visible spectrum of COF-DFB shows that its maximum absorption wavelength is 413.8 nm. These results indicate that COF-DFB possesses excellent photoelectric properties and demonstrates significant application potential in the field of photocatalysis.