Theoretical study on charge transfer properties of triphenylamino-ethynyl Polycyclic Aromatic Hydrocarbon derivatives

TL;DR

This paper develops a theoretical framework combining Marcus theory and simulations to understand and optimize charge transfer in triphenylamine-ethynylene fused acenes, guiding the design of high-mobility organic UV photodetectors.

Contribution

It introduces a novel 'backbone-functional group synergy' strategy and provides quantitative insights into molecular design for improved charge transport.

Findings

Sulfur doping reduces reorganization energy to 146.1 meV.

Asymmetric substitution decreases transfer integrals by 34%.

Backbone-focused orbital localization enhances mobility significantly.

Abstract

This study systematically investigates the regulation mechanisms of backbone topology (tri-/tetracyclic arenes), substitution positions, and functional groups on charge transport properties through molecular design of triphenylamine-ethynylene fused acene derivatives. By integrating Marcus charge transfer theory with kinetic Monte Carlo simulations, we demonstrate that sulfur-doped tricyclic arene backbones (benzodithiophene and anthracene) effectively suppress high-frequency vibrational modes reducing reorganization energy to 146.1 meV. Concurrent optimization of intermolecular $\pi$-$\pi$ slippage enhances 2D hole mobility. Notably, asymmetric charge transport pathways in 2,7-disubstituted pyrene(27DTEP) decrease transfer integrals by 34%, while 1,6-substitution (16DTEP)reconstructs HOMO orbital distribution and induces rotational stacking, boosting transfer integrals by 28% and improving mobility isotropy. We further propose a "backbone-functional group synergy" strategy, revealing that concentrated orbital localization on the backbone amplifies transfer integral gains, outweighing the 38% increase in reorganization energy and significantly enhancing mobility. These findings establish a theoretical framework and quantitative model for the rational design of high-mobility organic ultraviolet photodetectors.