Facile synthesized fluorine substituted benzothiadiazole based dopant-free hole transport material for high efficiency perovskite solar cell

A novel 4,4'-dimethoxy triphenylamine (donor), thiophene (bridge), and fluorine substituted benzothiadiazole (FBTD, acceptor) based molecule with D-A-D structure was synthesized via two steps from commercial precursors. The absorption, emission, thermal and electrochemical properties of the molecule was examined. The compound possesses planar molecular configuration, suitable energy level, high hole mobility and excellent thermal stability. When used as dopant-free hole transport material (HTM) in planar perovskite solar cell (PSC), the devices obtained a high power conversion efficiency (PCE) of 18.9% with good ambient stability by maintaining 87% of the initial efficiency after 480 h degradation. Those results enable us further understand the potential of FBTD as a promising building block of HTM for highly efficient PSCs.