Theoretical enhancement of the electronic and optical properties of a new D-π-A-π-D synthesized donor molecule for a new generation of fullerene-based bulk heterojunction (BHJ) for new organic solar cells devices

Samaher Chebil; Mourad Chemek; Tarek Mestiri; Kamel Alimi

doi:10.1016/j.jmgm.2022.108226

Theoretical enhancement of the electronic and optical properties of a new D-π-A-π-D synthesized donor molecule for a new generation of fullerene-based bulk heterojunction (BHJ) for new organic solar cells devices

J Mol Graph Model. 2022 Sep:115:108226. doi: 10.1016/j.jmgm.2022.108226. Epub 2022 May 26.

Authors

Samaher Chebil¹, Mourad Chemek¹, Tarek Mestiri¹, Kamel Alimi²

Affiliations

¹ Research laboratory, Asymmetric synthesis and molecular engineering of organic materials for organic electronics (LR18ES19), Faculty of science Monastir, 5000 Monastir, Tunisia.
² Research laboratory, Asymmetric synthesis and molecular engineering of organic materials for organic electronics (LR18ES19), Faculty of science Monastir, 5000 Monastir, Tunisia. Electronic address: kamel.alimi@fsm.rnu.tn.

PMID: 35667144
DOI: 10.1016/j.jmgm.2022.108226

Abstract

Herein, photophysical and electronic properties of a newly synthesized D-π-A-π-D benzothiadiazole derivative referred to 'R' molecule, were theoretically improved. Using Density Functional Theory (DFT), and it extended TDDFT methodologies, a news SMi (i = 1-4) benzothiadiazole derivatives are designed and studied by the modification of the acceptor (A) ring. Theoretical calculations show that going from R molecules to SMi ones, an intramolecular charge transfer is obtained. Indeed, the calculated dipole moment variation (μ_CT) between the ground and the first excited state increases. Consequently, an enhancement of the absorption in the visible part, and a reduction of the calculated optical band gap and the energy gap HOMO-LUMO are obtained. Furthermore, the calculated power conversion efficiency (PCE) factor of the bulk-heterojunction (BHJ) based on the investigated molecules (R and SMi, i = 1-4), as donor material and the fullerene (C60) as an acceptor one, increases drastically from 8% for R molecule to 13.5% for SM3 one according to Marks diagram. Finally, reduced density gradient analysis (RDG) analysis on the SM3-C60 designed composite proves the weak Vander-Waals interactions between the donor SM3 and the chosen acceptor C60.

Keywords: Charge transfer; Density functional theory (DFT); Organic solar cells; RDG; Reorganization energies; Small molecule donor.