Depicting the role of end-capped acceptors to amplify the photovoltaic properties of benzothiadiazole core-based molecules for high-performance organic solar cell applications

• Published in: Computational and theoretical chemistry 2022-05, Vol.1211, p.113669, Article 113669
• Main Authors: Ullah Rashid, Ehsan, Iqbal, Javed, Farhat Mehmood, Rana, El-Badry, Yaser A., Javaid Akram, Sahar, Ahmad Khera, Rasheed
• Format: Article
• Language: English
• Subjects: Benzothiadiazole; Computational analysis; Open-circuit voltage; Renewable energy sources; Transition density matrix
• ISSN: 2210-271X
• DOI: 10.1016/j.comptc.2022.113669

The results illustrate the efficient contribution of all the investigated molecules toward the bathochromic shift of the UV–visible absorption. All the investigated molecules show reduced band gap with increased oscillator strength, light harvesting efficiency. Open circuit voltage, fill factor as well as power conversion of all the investigated molecules (R, T1-T5) are analyzed by making their blend with a well-known donor molecule PTB7-Th. [Display omitted] •By modification of reference molecule, five new small molecules (T1-T5) are designed.•The optoelectronic properties of T1-T5 were compared with reference molecule.•The designed molecules possess improved diploe moment and enhanced intramolecular charge mobility.•The entitled molecules (T1-T5) have much better oscillator strength and light harvesting efficiency as compared to the reference molecule.•Electronic properties of T1-T4 molecules are compared with each other. In this study, the intention to improve the efficiency of OSCs, five molecules of A2-D-A1-D-A2 have been designed. Optoelectronic properties of all the investigated molecules are analyzed computationally by employing the DFT method with CAM-B3LYP functional at a 6-31G (d, p) basis set. By introducing acceptor groups to the terminal ends, it has been noticed that all the optoelectronic parameters of designed molecules have improved to a considerable extent when compared with the reference molecule, e.g., absorption properties, exciton mobility, molecular electrostatic potential (MEP), HOMO-LUMO band gap, light-harvesting efficiency (LHE), etc. Amongst all the designed molecules, T3 possesses the maximum absorption (λmax = 541 nm) with the smallest bandgap (4.21 eV), least excitation and binding energy i.e., (Ex = 2.29 eV) and (1.92 eV) respectively, as well as the smallest interaction coefficient (0.5877). While, T2 molecule has the maximum oscillator strength f = (3.51) with the most efficient light-harvesting efficiency (LHE = 0.9996). T1 with the least hole (λh = 0.01594) and electron (λe = 0.01723) reorganization energy values possesses better hole as well as electron mobility when compared with all other designed molecules. VOC is calculated by making a complex of investigated acceptor molecules with PTB7-Th donor molecules and the values obtained range from 2.27 to 3.22 eV. Additionally, the T4 molecule has a maximum open-circuit voltage (VOC) of 2.69 eV, VOC is directly related to the normalized VOC and FF so, T4 also possesses pr