Molecular Designing and Simulation‐Driven Exploration of Benzotrithiophene‐Based Semiconductors for Organic Photovoltaics

Abstract Small‐molecular hole transport materials (SM‐HTMs) are highly attractive due to their easy synthesis, low cost, and high performance when fabricated in organic solar cells (PSCs). Herein, we designed eight new scorpion‐shaped benzotrithiophene‐based (BTT) molecules (RIM1‐RIM8) by introducing π‐spacers and acceptors as side‐chain functional groups. We subsequently characterized these designed (RIM1‐RIM8) series by employing advanced quantum‐chemical approaches along with the synthetic reference molecule RIM. We extensively investigated the structure‐property relationship and the impact of end‐capped modifications on the optical, optoelectronics, charge‐carrier dynamics and photovoltaic characteristics. We also estimated the binding energy, reorganizational energies of holes and electrons, light harvesting efficiency, density of states, transition density matrix, electrostatic potential, dipole moment, and electron‐hole analysis. Among all the designed molecules, RIM4 shows the highest absorption at 615.67 nm, the lowest bandgap (2.46 eV) energy, and efficient charge‐carrier transport properties—which suggest RIM4 could be used efficiently in fabricating high‐performance organic and PSCs. Moreover, we also performed a donor/acceptor (RIM4:PC 70 BM) complex study to estimate the charge shifting from the HOMO of RIM4 to the LUMO of PC 70 BM at the donor/acceptor interface. Consequently, we suggest these newly designed scorpion‐shaped RIM1‐RIM 8 molecules for developing efficient next‐generation organic and PSCs.