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

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Molecular and biomolecular spectroscopy, 2021-01, Vol.244, p.118873, Article 118873
• Main Authors: Mehboob, Muhammad Yasir, Khan, Muhammad Usman, Hussain, Riaz, Ayub, Khurshid, Sattar, Abdul, Ahmad, Muhammad Kaleem, Irshad, Zobia, Saira, Adnan, Muhammad
• Format: Article
• Language: English
• Subjects: Benzodithiophene; Cyclopentadienylthiophenes; DFT; End-capped modifications; Organic solar cells
• ISSN: 1386-1425
• DOI: 10.1016/j.saa.2020.118873

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 (λe = 0.0044–0.0104 eV and λh = 0.0060–0.0090 eV). Moreover, H1-H5 molecules demonstrate red-shifting in absorption spectrum (λmax = 741–812 nm) as compare to R (λmax = 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. [Display omitted] •Five new acceptor materials having benzodithiophene core are designed for organic solar cells.•The structure–property relationship, and photovoltaic properties of designed molecules is studied.•All newly designed molecules have excellent opto-electronic properties with respect to reference compound.