Role of end-capped acceptor moieties on optoelectronic properties of small molecules featuring B–N covalent bond-based organic solar cells

It is now of vital importance to use non-fullerene small molecules with B–N integrated conjugate systems in solar cells. Contrary to carbon analogues, conjugate systems with B–N covalent bonds have special qualities that promise to advance solar cell optoelectronics, including broad optical absorption, low bandgaps, and high packing order. In four new compounds, BNT was used as a donor (C), benzene as a peripheral (P), and various acceptors as terminal moieties (A). To determine the optoelectronic properties, the selected B3LYP functional was paired with the 6–31G (d, p) basis set. The 6–31G (d, p) basis set was coupled with the chosen B3LYP functional to ascertain the optoelectronic characteristics. Comprehensive research was done on the parameters charge distribution, UV–Vis absorption spectra, exciton dynamics, electron–hole mobilities, frontier molecular orbitals (FMOs), and transition density matrix (TDM). The reorganization energy of the electron is the lowest of BNTM3 (0.0067 eV) indicating the highest electron mobility. Reduced bandgaps with red-shift, high charge mobilities, and high open-circuit voltage were found in all developed molecules. BNTM3 has the shortest HOMO–LUMO gap of 2.20 eV with the largest absorption maxima at 685 nm with wide absorption in the 600–800 nm range. BNTM1–BNTM4 are promising candidates for small molecule-based organic photovoltaics.