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

Abstract

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_max) except <b>AM6</b>. <b>AM1</b>-<b>AM4</b> molecules represented a narrow band gap (<i>E</i>_g) and low excitation energy values. The <b>AM1</b>-<b>AM4</b> and <b>AM6</b> molecules have higher electron mobility. Comparing <b>AM2</b> to the reference molecule reveals that <b>AM2</b> has higher hole mobilities. Compared to the reference molecule, all compounds have excellent light harvesting efficiency values compared to <b>AM1</b> and <b>AM2</b>. The natural transition orbital investigation showed that <b>AM5</b> and <b>AM6</b> had significant electronic transitions. The open-circuit voltage (<i>V</i>_oc) 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.