Impact of π-linker modifications on the photovoltaic performance of rainbow-shaped acceptor molecules for high performance organic solar cell applications

Non-fullerene acceptor (NFA) materials attracted a huge attention because of their tendency to improve the power conversion efficiency (PCE) of organic solar cells (OSCs). Herein, we intended to demonstrate the efficient designing of a series of Rain-bow shaped materials (LB1 to LB5). These acceptor materials are designed by various end-capped modifications in a synthetically reported pi-linker CH1007 molecule (reference R). The photovoltaic, optoelectronic, structural-property relationship, and physiochemical properties are specifically realized by using density functional theory (DFT) and time-dependent (TD-DFT) at B3LYP/6-31G (d,p). Our designed materials (LB1 to LB5) significantly occupied a narrower energy bandgap (E-g) (E-g = 1.87-2.01 eV) in contrast to R and found highly red-shifted in absorption spectrum with lower excitation energies. The reorganization energy studies showed that the newly designed materials (LB1 to LB5) exhibited a better electronic mobility (lambda(h) = 0.0153 to 0.0190) as compared with R (lambda(h) = 0.0194). The higher open circuit voltage (V-oc), and lower binding energy (Eb) values suggested that these designed materials (LB1 to LB5) are best fitted to prepare highly efficient OSCs devices. To study the charge transfer behavior, a donor:acceptor (D:A) blend study has also been performed to estimate an efficient charge transport phenomenon at the D:A interface. The outcomes of all analysis suggested that this designed series (LB1 to LB5) could be effective for the future development of highly efficient OSCs devices.