A theoretical approach for investigating the end-capped engineering effect on indophenine-based core for efficient organic solar cells

Abstract

The area of OPVs is attracting considerable attention in the quest for sustainable energy solutions due to their low-cost, tunable properties and diverse functionality. In this study, we have designed a series of seven indophenine-based molecules (IDA1–IDA7) for OSCs to fulfill the imminent energy requirements. This work uses the DFT approach to explore the geometrical and optoelectronic properties of newly designed molecules. To comprehensively assess the potential of these designed molecules for OSCs, a range of excited state parameters are evaluated at MPW1PW91/6-31G (d,p) level of DFT. It was found that the newly designed materials outperformed the IDR (reference) for notable attributes including deeper HOMO, red-shifted absorption (767–884 nm), lower band gaps (1.74–1.89 eV), and small hole–electron coulombic attraction (2.41–2.82 eV). Besides this, excited state charge transfer direction is mainly from central core to terminal acceptors elucidating their efficiency in the charge separation within OSCs. Moreover, V_oc has been estimated systemically in relation to the non-fullerene Y6 acceptor, and all planned donor molecules exhibited enhanced V_oc (0.79–1.04 V) than IDR (0.53 V). All the planned molecules manifested lower hole (0.185–0.217 eV) and electron reorganization energy (0.317–0.393 eV) than IDR (λ_h = 0.224, λ_e = 0.413 eV). In addition, the IDA3:Y6 blend manifested stronger CT characteristics, which are favorable for realizing high-performance OSCs. The proposed design strategy provides valuable insights to improve the photovoltaic performance of indophenine-based materials for OSCs.

Graphical Abstract