End-capped engineering of carbazole based dopant free hole transporting material with improved power conversion efficiency

Abstract

Perovskite solar cells (PSCs) belonging to third-generation of solar cells are reported to have better power conversion efficiency, cost-effectiveness, and many other benefits. This computational investigation focuses on designing five indolo(3,2-b) carbazole (ICZ) central core containing small hole transport materials (HTMs) to discover photovoltaic properties as donors for perovskite solar cells accompanied by enhanced charge mobility. New HTMs with A–π–D–π–A skeleton has been designed by thiophene-bridged end-capped acceptor engineering on reference molecule (ICZ-R). Absorption spectra, frontier MOs, density of state analysis, molecular electrostatic potential surfaces, transition density matrix, non-covalent interactions, iso-surface maps, and planarity parameters were analyzed through different softwares for better-predicting performance of perovskite solar cells. All tailored HTMs showed better absorption profiles. Among them, ICZ-D3 exhibited the maximum absorbance λmax at 695 nm in dichloromethane solvent and the greatest full-width half maximum (313.93 nm). ICZ-D2 showed the lowest Eg of 1.62 eV, and the highest dipole moment (8.35 D) in the solvent phase, showing admirable solubility. Designed HTMs exhibited decelerated HOMO values (−4.62 to −5.25), lower values of binding energies (0.0323–0.388 <0.542 eV), better intrinsic charge transfer percentage (10.74–72.71%>7.88), lower hardness (0.81–1.11 <1.78 eV) and greater softness values (0.90–1.23 >0.56 eV) as compared to ICZ-R. All designed HTMs demonstrated higher estimated VOC and power conversion efficiency (PCE=11.81–25.90%) than ICZ-R, leading to fruitful applications. ICZ-D4 resulted in the highest PCE (25.90%) with better VOC (1.25 eV). These outstanding findings paved a new way to develop better-performing HTMs for PSCs.