Quantum chemical modification of indaceno dithiophene-based small acceptor molecules with enhanced photovoltaic aspects for highly efficient organic solar cells

Abstract

In this computational work, with the aim of boosting the ultimate efficiency of organic photovoltaic cells, seven small acceptors (IDST1–IDST7) were proposed by altering the terminal-acceptors of reference molecule IDSTR. The optoelectronic characteristics of the IDSTR and IDST1–IDST7 molecules were investigated using the MPW1PW91/6-31G(d,p) level of theory, and solvent-state computations were examined using time-dependent density functional theory (TD-DFT) simulation. Nearly all the investigated photovoltaic aspects of the newly proposed molecules were found to be better than those of the IDSTR molecule e.g. in comparison to IDSTR, IDST1–IDST7 exhibit a narrower bandgap (E_gap), lower first excitation energy (E_x), and a significant red-shift in the absorbance maxima (λ_max). According to the findings, IDST3 has the lowest E_x (1.61 eV), the greatest λ_max (770 nm), and the shortest E_gap (2.09 eV). IDST1–IDST7 molecules have higher electron mobility because their RE of electrons is less than that of IDSTR. Hole mobility of IDST2–IDST7 is higher than that of the reference owing to their lower RE for hole mobility than IDSTR. By coupling with the PTB7-Th donor, the open circuit voltage (V_OC) of the investigated acceptor molecules (IDSTR and IDST1–IDST7) was calculated and investigation revealed that IDST4–IDST6 molecules showed higher V_OC and fill factor (FF) values than IDSTR molecules. Accordingly, the modified molecules can be seriously evaluated for actual use in the fabrication of OSCs with enhanced photovoltaic and optoelectronic characteristics in light of the findings of this study.