Design, synthesis and characterization of indolo[3,2-a]carbazole-based low molecular mass organogelators as hole transport materials in perovskite solar cells

Abstract

Hole transport materials (HTMs) used in third-generation perovskite solar cells (PSCs) have a significant role in enhancing power conversion efficiency (PCE). In this work, low-molecular-mass indolocarbazole-based HTMs (C_RICs) are developed as alternatives to the expensive benchmark HTM spiro-OMeTAD. These indolocarbazole-based HTMs (C_RICs) are prepared by a two-step synthesis strategy and have structural elements to control hydrophobicity, solubility, and thermal stability. The ground-state oxidation of C_RICs (−5.40 eV) matches well with the highest occupied molecular orbital (HOMO) of the perovskite (PVSK) material for efficient hole extraction similar to spiro-OMeTAD. Interestingly, the developed C_RICs exhibit excellent gelation properties in the presence of traces of water at room temperature. The gelation properties of C_RICs are expected to protect the perovskite material from deterioration by trapping the moisture when used as the HTMs in PSC devices.