Influence of end-capped engineering on 3-dimenional star-shaped triphenylamine-based donor materials for efficient organic solar cells

Star-shaped- triphenylamine-based (TPA) hole transporting materials (HTMs) are considered an up-and-coming candidate for developing efficient organic solar cells (OSCs). Therefore, we have designed partially oxygen bridged eight new novels (STRO1 – STRO8) and three-armed star-shaped HTMs with TPA core for the future development of efficient OSCs devices. Their photovoltaic, optical, and charge transport (CT) characteristics were studied and compared with the reference molecule (R). These designed materials have been characterized theoretically using various density functional theory (DFT) and time-dependent (TD-DFT) calculations. These planar configurated star-shaped molecules exhibited a red-shifted absorption, deeper HOMO levels, and improved extinction coefficients, enabling them to offer good phase separation morphology during blend formation. Furthermore, the distribution behavior of frontier molecular orbitals (FMOs), optical properties, open-circuit voltages, the density of states (DOS), transition density matrix (TDM), and reorganization energies of holes and electrons of the designed star-shaped molecules have been investigated. Besides, the complex study of STRO/PC61BM revealed the charge shifting process at the donor–acceptor interface. Therefore, our projected approach is a prerequisite in designing small molecule (SM)-based desirable photovoltaic materials for efficient OSCs, and light-emitting diodes (LEDs), and afterwards, these materials are suggested to the experimentalist for synthesis and to fabricate efficient photovoltaic devices.