Designing of benzodithiophene core-based smallmolecular acceptors for efficient non-fullerene organic solar cells

Nowadays, organic solar cells (OSCs) with non-fullerene electron acceptors provide the highest efficiencies among all studied OSCs. To further improve the efficiencies of fullerene-free organic solar cells, end-capped acceptor modification is made with strong electron withdrawing groups. In this report, we have theoretically designed five new novel Benzodithiophene core-based acceptor molecules (H1-H5) with the aim to study the possible enhancement in photophysical, optoelectronic, and photovoltaic properties of newly designed molecules. The end-capped acceptor modification of famous and recently synthesized FBDIC molecule has been made with strong electron withdrawing groups. Density functional theory and time-dependent-density functional theory are extensively used to study the structural-property relationship, optical properties and various geometrical parameters like frontiermolecular orbitals alignment, excitation and binding energy, transition density matrix along with open circuit voltage, density of states and dipole moment. Commonly, low reorganization energies (hole and electron) afford high charge mobility and our all designed systems are enriched in aspect (lambda(e) = 0.0044-0.0104 eV and lambda(h) = 0.0060-0.0090 eV). Moreover, H1-H5 molecules demonstrate red-shifting in absorption spectrum (lambda(max) = 741-812 nm) as compare to R (lambda(max) = 728 nm). Low excitation and binding energies with low HOMO (highest occupied molecular orbital)-LUMO (lowest unoccupied molecular orbital) energy gap of H1-H5 suggested that designed molecules are better and suitable candidates for high performance organic solar cell. Results of all analysis indicate that this theoretical framework demonstrates that end-capped acceptors modification is a simple and effective alternative strategy to achieve the desirable optoelectronic properties. Therefore, H1-H5 are recommended to experimentalist for out-looking future developments of highly efficient solar cells. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The study focuses on the theoretical design of five novel Benzodithiophene core-based acceptor molecules to enhance the performance of organic solar cells. End-capped acceptor modification with strong electron withdrawing groups has resulted in high charge mobility and red-shifting in absorption spectrum for the designed molecules. The low excitation and binding energies, along with a low HOMO-LUMO energy gap, make the H1-H5 molecules suitable candidates for high-efficiency organic solar cells.