Approach toward Low Energy Loss in Symmetrical Nonfullerene Acceptor Molecules Inspired by Insertion of Different π-Spacers for Developing Efficient Organic Solar Cells.

In this quantum approach, by adding bridge/π-spacer fragments between the donor and acceptor parts of a newly constructed DF-PCIC (A-D-A type) molecule, it is the aim to improve the photovoltaic characteristics of organic solar cells (OSCs). After π-spacer insertion into the reference molecule (), six new molecules ( to ) were designed. The optoelectronic attributes of newly inspected molecules were theoretically calculated using MPW1PW91/6-31G(d,p) level of theory. All newly proposed molecules possessed a lower band gap (), a higher value of absorption, lower reorganization energy, greater dipole moment, and lower energies of excitations than the molecule. The frontier molecular orbital study proclaimed that the molecule has the lowest band gap of 1.62 eV in comparison to the 2.41 eV value of . Absorption properties represented that and molecules show the highest absorption values of up to 1006 and 1004 nm, respectively, in the near-infrared region. Regarding the reorganization energy, has the lowest value of λ (0.0683896 eV) and the lowest value of λ (0.1566471 eV). and manifested greater dipole moments with the values of 5.514665 and 7.143434 D, respectively. The open circuit voltage () of all the acceptors was calculated with , a donor complex. and molecules showed higher values of and fill factor than the molecule. Based on the given results, it was supposed that all the newly presented molecules might prove themselves to be better than the reference and thus might be of great interest to experimentalists. Thus, they are suggested to be used to develop proficient OSC devices with improved photovoltaic prospects in the near future.