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 (CRICs) are developed as alternatives to the expensive benchmark HTM spiro-OMeTAD. These indolocarbazole-based HTMs (CRICs) are prepared by a two-step synthesis strategy and have structural elements to control hydrophobicity, solubility, and thermal stability. The ground-state oxidation of CRICs (−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 CRICs exhibit excellent gelation properties in the presence of traces of water at room temperature. The gelation properties of CRICs are expected to protect the perovskite material from deterioration by trapping the moisture when used as the HTMs in PSC devices.