T‑Shaped-N-Doped\nPolycyclic Aromatic Hydrocarbons:\nA New Concept of Dopant-Free Organic Hole-Transporting Materials for\nPerovskite Solar Cells

Although\nmetal halide perovskites are positioned as the most powerful\nlight-harvesting materials for sustainable energy conversion, there\nis a need for a thorough understanding of molecular design principles\nthat would guide better engineering of organic hole-transporting materials,\nwhich are vital for boosting the performance and stability of perovskite\nsolar cells. To address this formidable challenge, here, we developed\na new design strategy based on the curved N-doped polycyclic aromatic\nhydrocarbon merged with T-shaped phenazines being decorated with (phenyl)-di-<i>p</i>-methoxyphenylamine (OMeTAD)N-PAH23/24 and -3,6-ditertbutyl\ncarbazole (TBCz)N-PAH25/26. As N-PAH23/24 exhibited satisfying\nthermal stability, the comparative studies performed with various\nexperimental and simulation methods revealed a pronounced correlation\nbetween the depth of the central cyclazine core and the form of the\nT-shape units. This proved to be a crucial factor in controlling their\nπ–π intermolecular interaction as well as self-assembly\nbehavior with the perovskite layer, leading to enhanced humidity resistance,\noperational stability, and a maximum power conversion efficiency of\n20.39% denoted for N-PAH23, which is superior to the benchmarked device\nwith doped spiro-OMeTAD (19.23%). These studies not only resulted\nin optimized stability and device performance but also opened a conceptually\nnew chemical space in the photovoltaic technology.