High-Efficiency and Low-Energy-Loss Organic Solar Cells Enabled by Tuning the End Group Modification of the Terthiophene-Based Acceptor Molecules to Enhance Photovoltaic Properties.

In the current study, six nonfullerene small acceptor molecules were designed by end-group modification of terminal acceptors. Density functional theory calculations of all designed molecules were performed, and optoelectronic properties were computed by employing different functionals. Every constructed molecule has a significant bathochromic shift in the maximum absorption value (λ) except . - molecules represented a narrow band gap () and low excitation energy values. The - and molecules have higher electron mobility. Comparing to the reference molecule reveals that has higher hole mobilities. Compared to the reference molecule, all compounds have excellent light harvesting efficiency values compared to and . The natural transition orbital investigation showed that and had significant electronic transitions. The open-circuit voltage () values of the computed molecules were calculated by combining the designed acceptor molecules with PTB7-Th. In light of the findings, it is concluded that the designed molecules can be further developed for organic solar cells (OSCs) with superior photovoltaic abilities.