Computational Design of Crescent Shaped Promising Nonfullerene Acceptors with 1,4-Dihydro-2,3-quinoxalinedione Core and Different Electron-withdrawing Terminal Units for Photovoltaic Applications

This study aims to design a series of nonfullerene acceptors (NFAs) for photovoltaic applications having 1,4-dihydro-2,3-quinoxalinedione fused thiophene derivative as the core unit and 1,1-dicyanomethylene-3-indanone (IC) derivatives and different π-conjugated molecules other than IC as terminal acceptor units. All the investigated NFAs are found air-stable as the computed highest occupied molecular orbitals (HOMOs) are below the air oxidation threshold (ca. -5.27 eV vs saturated calomel electrode). The studied NFAs can act as potential nonfullerene acceptor candidates as they are found to have sufficient open-circuit voltage (V_oc) and fill factor (FF) ranging from 0.62 to 1.41 V and 83%-91%, respectively. From the anisotropic mobility analysis, it is noticed that the studied NFAs except dicyano-rhodanine terminal unit containing NFA, exhibit better electron mobility than the hole mobility, and therefore, they can be more promising electron transporting acceptor materials in the active layer of an organic photovoltaic cell. From the optical absorption analysis, it is noted that all the designed NFAs have the maximum absorption spectra ranging from 597 nm-730 nm, which lies in the visible region and near-infrared (IR) region of the solar spectrum. The computed light-harvesting efficiencies for the PM6 (thiophene derivative donor selected in our study):NFA blends are found to lie in the range of 0.96-0.99, which indicates efficient light-harvesting by the PM6:NFA blends during photovoltaic device operation.