Addition of Diphenylamine Branches: An Efficient Approach to Highly Improve the Hole-Transporting Property of Phenylazo-Indole Components for Use in Perovskite Solar Cells

Abstract

With the aim of achieving cost-effective, efficient hole transport materials (HTMs) for use in perovskite solar cells, we investigate the nature and characteristics of some materials based on phenylazo-indole (PAZI) branched by the two derivatives of diphenylamine (DPA) (−OMeDPA and −NH2DPA) as novel HTMs. We exploit precise computational techniques including density functional theory (DFT) and time-dependent DFT along with the Marcus theory to make an accurate estimation on the optical and electrochemical properties of the designed materials. Our results show a significant increase in the values of Stokes shift and hole mobility when the diphenylamine derivatives connect to the core (PAZI) by a phenyl group (OMeDPA-Ph-PAZI and NH2DPA-Ph-PAZI) instead of a direct connection. At the molecular level, Me-PAZI-5-OMeDPA and NH2DPA-Ph-PAZI with proper HOMO levels (−5.32 and −5.34 eV) and Stokes shifts (47.61 and 111.1 nm), good stabilities (2.50 and 2.34 eV), and higher hole mobilities (6.368 × 10–3 and 3.528 ×...