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

Muhammad Yasir Mehboob; Muhammad Usman Khan; Riaz Hussain; Riaz Hussain; Khurshid Ayub; Abdul Sattar; Muhammad Kaleem Ahmad; Zobia Irshad; Saira; Muhammad Adnan

doi:10.1016/j.saa.2020.118873

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

Spectrochim Acta A Mol Biomol Spectrosc. 2021 Jan 5:244:118873. doi: 10.1016/j.saa.2020.118873. Epub 2020 Aug 22.

Authors

Affiliations

¹ Department of Chemistry, University of Okara, Okara 56300, Pakistan.
² Department of Chemistry, University of Okara, Okara 56300, Pakistan; Department of Applied Chemistry, Government College University, Faisalabad 38000, Pakistan. Electronic address: usman.chemistry@gmail.com.
³ Department of Chemistry, University of Okara, Okara 56300, Pakistan. Electronic address: riazhussain@uo.edu.pk.
⁴ Department of Chemistry, University of Education Lahore, D.G. Khan Campus, Dera Ghazi Khan 32200, Pakistan.
⁵ Department of Chemistry, COMSATS University, Abbottabad 22060, Pakistan.
⁶ Department of Biosciences, COMSATS Institute of Information and Technology Islamabad, Sahiwal campus, Pakistan.
⁷ Graduate School, Department of Chemistry, Chosun University, Gwangju 501-759, Republic of Korea.
⁸ Graduate School, Department of Chemistry, Chosun University, Gwangju 501-759, Republic of Korea. Electronic address: adnan@chosun.kr.

PMID: 32889342
DOI: 10.1016/j.saa.2020.118873

Abstract

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 frontier molecular 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 (λ_e = 0.0044-0.0104 eV and λ_h = 0.0060-0.0090 eV). Moreover, H1-H5 molecules demonstrate red-shifting in absorption spectrum (λ_max = 741-812 nm) as compare to R (λ_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.

Keywords: Benzodithiophene; Cyclopentadienylthiophenes; DFT; End-capped modifications; Organic solar cells.