Computational study of new small molecules D-A based on triphenylamines for bulk heterojunction solar cells (BHJ)

In this computational study, four donor–acceptor (D–A) small molecules were constructed using indacenodithiophene triphenylamine (IDTTPA) as the donor, with modifications made to the acceptor units intended for use in organic bulk heterojunction (BHJ) solar cells. Their electrical and optical properties were determined through density functional theory (DFT) and time-dependent DFT (TD-DFT) techniques. To ascertain the impact of acceptor group modifications on intramolecular electron delocalization and light absorption capabilities, several key variables were examined. Based on the results, it was determined that molecule SM4 demonstrated the best performance among the designed compounds. It exhibited a maximum wavelength of 594 nm, a narrow energy gap of 1.91 eV, a low-lying HOMO energy level of −4.512 eV in its absorption spectra, and a theoretical power conversion efficiency (PCE) of 8 %. This research provides valuable insights for the development of efficient D-A compounds for use in organic solar cells.