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

Molecular modelling of fused heterocycle-based asymmetric non-fullerene acceptors for efficient organic solar cells

Heterocycle substitution plays a key role in designing an ultra-narrower bandgap (ultra-NBG) small molecule-based (SM) non-fullerene acceptors (NFAs) for organic solar cells (OSCs). The NFAs molecules have great significance because of their ability to improve efficiency, narrow band gap, better charge separation, higher absorption spectra, and overall device performance. However, the impact of heterocycles such as benzoselenadiazole (BSe) on optoelectronics characteristics is still unclear. Herein, seven asymmetric NFAs based on BSe electron-deficient fused-ring core were designed from the reference (R) BTP-Se. All seven NFAs exhibited a strong absorption phenomenon from visible to near-infrared (NIR) region, corresponding to the ultra-NBG and lower excitation energy (Ex). These designed asymmetric materials (BTP1-BTP7) along with R are fully characterized theoretically with various advanced quantum chemical techniques. The optical and optoelectronics features were explored with density functional theory (DFT) and time-dependent (TD-DFT) simulations. The in-depth calculations related to density of state (DOS), transition density of state (TDM), open-circuit voltage, fill factor, and reorganization energy of electrons and holes are performed intensively. BTP3 has an optical band gap narrow of 1.76 eV and an outstanding absorption maximum of 906.85 nm. For charge transfer, a donor:acceptor complex study of BTP3:PBDBT is carried-out. We hope that this may provide a favourable strategy for building highly efficient near infrared (NIR)-based OSCs