Optoelectronic properties of one-dimensional molecular chains simulated by a tight-binding model

TL;DR

This study uses a tight-binding model combined with first-principles calculations to analyze the optical properties of a one-dimensional zinc-phthalocyanine molecular chain, successfully interpreting experimental spectra and highlighting exciton coupling effects.

Contribution

First application of tight-binding calculations combined with first-principles methods to study optical properties of a molecular chain, emphasizing exciton interactions.

Findings

Successfully interpreted experimental UV-Vis spectra.

Highlighted the importance of exciton coupling.

Compared with ab initio results showing similar absorption features.

Abstract

Studying optical properties of organic materials is important due to the rapid development of organic light-emitting diodes, solar cells, and photon detectors. Here for the first time we have performed tight-binding calculations for singlet excitons, in combination with first-principles calculations of the excited states in molecular dimers, to describe the optical properties of a zinc-phthalocyanine one-dimensional molecular chain. We have included the intra-molecule and charge-transfer excitations and the coupling between them. Our calculations have successfully interpreted a body of experimental UV-Vis optical spectra of transition-metal phthalocyanines. Compared with the previous ab initio calculations for a molecular dimer, the optical absorptions at the split peaks of the Q-bands can be comparable, which indicates the importance of the coupling between the intra-molecular and charge-transfer excitons.