Molecular Design of the Triphenylamine Substitution on Isoindigo-Based as Promising Hole Transport Materials for Perovskite Solar Cell

The performance of perovskite solar cells (PSCs) controlling the hole mobility is the fundamental importance. The development of novel hole transport materials (HTMs) with good stability, low cost and high hole mobility for PSCs has attracted much attention for researchers. In this work, new isoindigo-based HTMs substituted with two triphenylamine (TPA) with the donor-acceptor-donor (D-A-D) architecture, were designed computationally. The effect of π-extension influence on the charge transfer process was investigated by insertingof two vinyl groups between acceptor and donor parts (D-π-A-π-D). The correlation between electronic structure and hole transport properties of the designed HTMs was determined by tuning the connection between donor and acceptor. The ground state of the HTMs was fully optimized by DFT method at B3LYP/6-31G(d,p), and the excited state, absorption and emission properties of the  HTMs were carried out by using the TD-DFT at cam-B3LYP/6-31G(d,p) in dichloromethane solvent based on the conductor-like polarizable continuum model (C-PCM). The calculated HOMO, LUMO and band gap values of the HTMs showed higher values than that of MAPbI3 (perovskite). Hence, the charge distribution in HOMO and LUMO of our designed structures could qualitatively predicted the carrier injection and transportation in the PSCs. The adsorption spectra were broader, indicating that the proposed HTMs absorbed a large amount of visible light, which might impact the electron delocalization. This designed HTMs would have the potential for synthesis of new HTMs