Design and evaluation of phthalocyanine-functionalized triselenasumanene molecules as multifunctional hole transport materials in perovskite and donor materials in organic solar cells: A DFT study

• Three novel HTMs (Tr-Ph1 to Tr-Ph3) based on a triselenosumanene (TRSS) core functionalized with phthalocyanine units were designed and evaluated. • Functionalization significantly reduced the bandgap from 4.27 eV (TRSS) to as low as 1.97 eV (Tr-Ph3) in the gas phase, enhancing light absorption. • Power conversion efficiency (PCE) of the L8-BO: Tr-Ph1 organic solar cells reached up to 21.08% • Tr-Ph3 showed a notable hole-to-electron reorganization energy ratio (λ h /λ e = 2.11 ), indicating excellent hole-transport characteristics. This study aims to design and introduce multifunctional organic molecules based on Triselenasumanene (TRSS) functionalized with one to three organic Phthalocyanine units (Tr-Ph1 to Tr-Ph3) for potential use as donors in organic solar cells (OSCs) and hole transport materials (HTMs) in both OSCs and perovskite solar cells (PSCs). Using DFT and TD-DFT methods with the B3LYP functional and 6-31G(d,p) basis set, the structures were optimized and analyzed. The results showed that increasing the number of Phthalocyanine units significantly reduces the energy gap (from 4.29 eV for TRSS to 1.97 eV for Tr-Ph3), induces a strong red shift in maximum absorption wavelength, enhances absorption intensity (over threefold), increases dipole moment, decreases the first excitation energy (nearly half), doubles the light-harvesting efficiency (LHE), reduces binding energy, and nearly doubles the λ e /λ h ratio. These findings support the suitability of the designed molecules as donors in OSCs and HTMs in both OSCs and PSCs. Osc simulations with acceptors such as ITIC, ITIC-Th, Y6, L8-BO, and BTP-eC9 showed that L8-BO:Tr-Ph1 achieves the highest PCE of 21.08%. Moreover, HOMO–LUMO alignment with MAPbI 3 and FAPbI 3 confirms their potential as HTMs. The high efficiency, synthetic accessibility, non-toxicity, multifunctionality, and eco-friendly nature of these molecules offer a promising path for next-generation OSCs and PSCs.