Dopant-Free Hole-Transport Materials Based on 2,4,6-Triarylpyridine for Inverted Planar Perovskite Solar Cells

New building blocks of cores and periphery groups for organic hole-transporting materials (HTMs) have been paid much attention for recent development in perovskite solar cells (PSCs). In this work, we applied facile synthesis to join a 2,4,6-triarylpyridine building block for new HTMs based on a pyridine core by cheap industrial initial materials. The three small molecules, namely, D104, D105, and D106, were used in the pristine state. To the best of our knowledge, pyridine-cored dopant-free HTMs have not been reported in PSCs. The changing periphery 4-methoxyphenyl and bis(4-methoxyphenyl)amine groups formed different Y-shapes. Under 1 sun conditions, the devices achieved an increased power conversion efficiency (PCE) of 16.28%, 17.40%, and 18.24% for D104, D105, and D106. They displayed great potential with improved stability in inverted planar PSCs. The unencapsulated device in ambient environment (30% RH) based on D104, D105, and D106 retained 33%, 70%, and 75% of the initial PCE after 275 h.