End‐Capped Molecular Engineering of S‐Shaped Hepta‐Ring‐Containing Fullerene‐Free Acceptor Molecules with Remarkable Photovoltaic Characteristics for Highly Efficient Organic Solar Cells

Abstract

Nonfullerene acceptor materials are getting more and more attention from the scientific community because of their various applications in photovoltaic energy devices. Herein, a series of eight new S‐shaped nonfullerene acceptors (SY1–SY8) with end‐capped molecular modeling of IDTP‐4F (R) is designed. These designed materials are theoretically characterized along with the reference molecule R to investigate their structural‐property relationship, photophysical, and optoelectronic properties with density functional theory and time dependent calculations. Moreover, the geometric specifications such as alignments of frontier molecular orbitals, excitation and binding energy, hole‐electron overlap, density of states, overlap density of states, molecular electrostatic potential, open circuit voltage, transition density matrix, and reorganizational energy of electron and hole have also been investigated and compared with the experimentally synthesized reference molecule R. A highly red‐shifting behavior along, with a high charge mobility of electrons is realized after these end‐capped modifications in all designed molecules. Moreover, all designed molecules have lower binding and excitation energies as compared to reference molecule R. After these analyses, it is realized that the newly designed molecules (SY1‐SY8) are better than R, thus these molecules are recommended to experimentalists for the future development of highly efficient OSCs.