A Thioxanthenothioxanthene-based Hole Transporter with 2D Molecular Stacking for Efficient and Thermostable Perovskite Solar Cells

Maintaining persistent thin-film morphology under certain thermal stress is desirable for durable operation of multi-layer organic optoelectronic devices. We herein report a thioxanthenothioxanthene-centered hole-transporter (N3,N3,N9,N9-tetrakis(4-methoxyphenyl)thioxantheno[2,1,9,8-klmna]thioxanthene-3,9-diamine, TXTX-OMeDPA) characteristic of two-dimensional molecular stacking in a single crystal. TXTX-OMeDPA can be solution-processed into smooth thin films with suitable energy level and good hole mobility, allowing for the fabrication of perovskite solar cells with an impressive power conversion efficiency of 22.2% when measured under illumination of AM 1.5G sunlight. The remarkable morphological stability of TXTX-OMeDPA-based thin film ensures good stability for perovskite solar cells not only stored at 60 °C in the dark but also operated under equivalent full sunlight at 60 °C.