Optoelectronic behavior of spirocyclopentadithiophene in lattice aromatics

Abstract

Context

This study investigates the influence of intramolecular π-π stacking interactions on the optoelectronic properties of spirocyclopentadithiophene (spiro-CPDT)-based latticed molecules (GS-CPDT, HGS-CPDT1, and HGS-CPDT2) to optimize their charge transport characteristics. Density functional theory was employed to analyze molecular geometries, frontier molecular orbitals, adiabatic ionization potentials (IP_a), electron affinities (EA_a), and reorganization energies (λ). Crystal structure modeling using the Dreiding force field and computational evaluation of electronic coupling parameters (V_e, V_h) and charge-transfer rate constants (k_e, k_h) were performed to assess intramolecular π-π stacking effects. Results reveal that lattice-induced π-stacking configurations significantly reduce reorganization energies (λ_e = 0.223 eV, λ_h = 0.343 eV) while enhancing charge-transfer rate constants (~ 10¹¹ s⁻¹), demonstrating improved charge transport efficiency compared to conventional spiro-CPDT systems. These findings establish fundamental structure–property relationships for spiro-aromatic hydrocarbons, offering critical theoretical guidance for designing organic electronic materials with tailored charge transport capabilities.

Methods

The molecular energy, molecular structure, molecular orbitals, and other properties of all molecules designed in this paper were calculated using functional B3LYP and basis set 6-31G(d). Based on these calculations, tasks such as optimizing the ground state geometry of the molecules, calculating electrostatic potential, and optoelectronic properties were carried out. The weak interactions of molecules were investigated using Multiwfn 3.8 and VMD. Finally, the molecular crystal structure was predicted using the Metamorph module in Materials Studio 2020, and the dimer of the studied molecule was obtained.