End-capped modification of Y-Shaped dithienothiophen[3,2-b]-pyrrolobenzothiadiazole (TPBT) based non-fullerene acceptors for high performance organic solar cells by using DFT approach

In this study, we have conducted several computational procedures to perform end group modifications through thiophene bridges in Y-series acceptor (Y5) and devised five new compounds (V1-V5) and Rb (reference Y5 with thiophene bridges). By operating a computer-based software, the concept of Density functional theory (DFT) was employed on these molecules to study their planarity, energy gaps, electronic distributions, charge separations, light absorption ranges, light harvesting abilities, excitation and binding energies, open-circuit voltage, reorganizational energies, and dipole moments. This research disclosed that devised compounds have superiorities over R and Rb in many of these properties, making them a good option for developing outstanding OSCs. These devised compounds have exhibited the best results in terms of red shift in absorption band, higher dipole moment in chloroform (except V2) leading to enhanced crystallinity, lower excitation, and reorganization energies, which implies their higher intramolecular charge transfer rate. All designed molecules showed significant potential as acceptors and showed comparable values of open-circuit voltage with donor material PTB7-Th. It is estimated from the results that the optoelectronic properties of Rb (with the insertion of TB) and in some cases of developed molecules (with TB addition and end-group modification) have improved to a considerable extent. Based on these findings, devised compounds should be considered in order to fabricate OSCs with boosted photovoltaic attributes.