Role of 9-phenyl-9H-carbazole based hole transport materials for organic and perovskite photovoltaics

Abstract

The present study has focused on designing and characterizing ten novel (SS1-SS10) hole transport materials (HTM) for perovskite solar cells (PSCs). The objective is to enhance power conversion efficiency (PCE) and improve these devices' durability. A systematic investigation has been carried-out to investigaye the optoelectronic properties of these HTMs. Density functional theory (DFT) and time-dependent density functional theory (TD-DFT) have been employed to analyze the structures and optical features of these designed HTMs. The calculations included the arrangement of frontier molecular orbitals (FMO), open-circuit voltages (Voc), the density of states (DOS), transition density matrix (TDM), power conversion efficiency (PCE), reorganizational energies of electrons and holes, charge transfer analysis, and molecular electrostatic potential (MEP). Newly designed molecules (SS1-SS10) exhibit promising optoelectronic features with narrower energy gap (ranges from 1.41 eV to 0.64 eV) and absorbed maximum absorption wavelength (546 nm) compared to the reference molecule which have a gap of 3.41 eV and wavelength of 414.88 nm. The designed molecules also have high open-circuit-voltage values of 0.92–1.08 and proficient hole and electron transport abilities making them strong candidates when blended with the polymer PC70BM. The computed value of R for λe is 0.0082. The lowest reorganisation energy for electrons appears in SS8, SS3, and SS5, showing strong charge mobility within the acceptor and donor sections. The reorganisation energy of hole (λh) for R was discovered to be 0.0060, among all the designed molecules SS6 has the highest λh value. The study highlights that efficient molecular design and strategy are necessary for developing desirable photovoltaic precursors best suited for perovskite organic solar cells. The modeled materials SS1-SS10 are recommended for future synthesis and development of cost-effective organic solar cell devices.