Phenoxazine‐benzimidazolium ionic hole transport material for perovskite solar cells

Abstract

AbstractA novel organic ionic material, hole transport material‐1 (HTM‐I), was synthesized and characterized as a hole transport material for perovskite solar cells (PSCs), with the aim of replacing 2,2',7,7'‐Tetrakis[N,N‐di(4‐methoxyphenyl)amino]‐9,9'‐spirobifluorene (Spiro‐OMeTAD). HTM‐I was designed to incorporate both phenoxazine and benzimidazolium iodide salt structures, and its chemical structure was confirmed using 1H NMR and high‐resolution mass spectrometry. Differential scanning calorimetry measurements revealed that HTM‐I maintained an amorphous phase throughout the temperature range of −60 – 200 °C, and thermogravimetric analysis showed good thermal stability up to 220 °C. To evaluate its potential as a hole transport layer, perovskite solar cells were fabricated using a fluorine‐doped tin oxide (FTO)/compact‐TiO2/(Cs/FA/MA)Pb(I/Br)3/hole transport layer/Au configuration. The resulting n–i–p planar structure exhibited a power conversion efficiency of 10.4%.