  This study aims to design a series of non-fullerene acceptors (NFAs) for
photovoltaic applications having 2,3-quinoxalinedione,1,4-dihydro fused
thiophene derivative as the core unit and 1,1-dicyanomethylene-3-indanone (IC)
derivatives and different {\pi}-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 non-fullerene acceptor candidates as they are found to have
sufficient open-circuit voltage (Voc) and fill factor (FF) ranging from
0.62-1.41 eV 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 infra-red (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 0.9589-0.9957, which
indicates efficient light-harvesting by the PM6:NFA blends during photovoltaic
device operation.
