Asymmetric 3D Hole-Transporting Materials Based on Triphenylethylene for Perovskite Solar Cells

Abstract

Two asymmetric three-dimensional (3D) hole-transporting materials (HTMs) containing a triphenylethylene core and peripheral diphenylamine/triphenylamine moieties are first synthesized and successfully used in perovskite solar cells (PSCs). Both HTMs are obtained from facile preparation procedures and simple purification techniques. The X-ray diffraction, aggregation-induced emission properties, absorption and emission spectra, electrochemical properties, thermal stability, density functional theory calculations, hole mobility, scanning electronic microscopy, atomic force microscopy, steady-state and time-resolved photoluminescence, water contact angles, and photovoltaic parameters of the PSCs are compared. The highest power conversion efficiency increases from 12.57% (CJ-02) to 18.56% (CJ-01), rivaling that obtained from the state-of-the-art 2,2′,7,7′-tetrakis(N,N-di-p-methoxyphenylamine)-9,9′-spirobifluorene (spiro-OMeTAD) (18.69%). Further, the lab synthetic cost of CJ-01 is only about 15.5% of the price of commercial spiro-OMeTAD, and the concentration of CJ-01 solution for device fabrication is less than half of the concentration of spiro-OMeTAD solution (30.0 vs 72.3 mg mL–1). These results demonstrate that the propeller-shaped compounds with a highly twisted conformation are readily available and promising alternative HTMs for PSCs. Moreover, an applicable strategy to design new HTMs with 3D structure for achieving highly efficient PSCs is proposed.