Charge transfer excitons in optical absorption spectra of C60-dimers and polymers

TL;DR

This study investigates charge-transfer exciton effects in the optical absorption spectra of C60-dimers and polymers using a theoretical model, revealing how conjugation and doping influence CT components.

Contribution

It introduces a detailed theoretical analysis of CT excitons in C60 systems considering conjugation and doping effects, using a combined Hartree-Fock and configuration interaction approach.

Findings

CT-component increases with smaller conjugation, saturates at intermediate, decreases at large conjugation.

Doped systems show smaller CT-components than neutral, indicating shorter electron-hole distances.

Optical spectra variations depend on conjugation and doping levels.

Abstract

Charge-transfer (CT) exciton effects are investigated for the optical absorption spectra of crosslinked C60 systems by using the intermediate exciton theory. We consider the C60-dimers, and the two (and three) molecule systems of the C60-polymers. We use a tight-binding model with long-range Coulomb interactions among electrons, and the model is treated by the Hartree-Fock approximation followed by the single-excitation configuration interaction method. We discuss the variations in the optical spectra by changing the conjugation parameter between molecules. We find that the total CT-component increases in smaller conjugations, and saturates at the intermediate conjugations. It decreases in the large conjugations. We also find that the CT-components of the doped systems are smaller than those of the neutral systems, indicating that the electron-hole distance becomes shorter in the doped C60-polymers.