Novel thieno-imidazole salt-based hole transport material for dopant-free, efficient inverted perovskite solar cell applications

A unique quaternary iodide salt of thieno-imidazole, AI110, is designed, prepared and tested on an inverted (p-i-n) architecture perovskite solar cell (PSC) as a dopant-free hole transport material (HTM). The opto-electronic and power conversion properties of this novel aryl salt HTM are well characterized. The inverted PSC based on AI110 without any dopants and additional interlayers using the simplest device structure affords the best efficiency of 14.90%, which is much higher than those of the most widely used HTMs, Spiro-OMeTAD (11.84%) and PEDOT:PSS (12.55%). The superior performance of the aryl salt AI110 HTM is due to its significant capabilities of film formation, charge extraction, and hole mobilities which result in reducing current loses and charge recombination and thus increasing power conversion.