Fluorophenylhydrazine-Modulated Pure-Red Tin-Based Perovskite LEDs With 99% Rec. 2020 Gamut Coverage for Active-Matrix Displays

Two-dimensional tin (Sn)-based perovskite light-emitting diodes (PeLEDs), featuring pure-red emission and eco-friendly characteristics, show great potential in wide color-gamut displays. However, their electroluminescence performance still lags significantly behind that of the lead-based counterparts, primarily due to the challenges of fast crystallization rate and undesired self-oxidation of Sn 2+ to Sn 4+ . Here, we report a rational molecular design strategy using 3,5-difluorophenylhydrazine hydrochloride (2FPHCl), which provides both reduction and passivation functionalities. The fluorine substituents form hydrogen bonds with TEA + in TEA 2 SnI 4 to modulate the crystallization process, while the hydrazine group acts as a reductant to suppress Sn 2+ oxidation. Consequently, defects arising from fast crystallization and self-oxidation in tin-based perovskites are simultaneously mitigated. The optimized pure-red perovskite films exhibit a sixfold enhancement in photoluminescence quantum yield, along with more balanced carrier injection. As a result, the state-of-the-art pure-red PeLEDs achieve an external quantum efficiency of 11.7%, a Rec. 2020 color-gamut coverage of 99%, and a microsecond-scale response. This strategy further enables large-area devices with emitting areas up to 12.25 cm 2 and the first tin-based perovskite active-matrix displays integrated with a thin-film transistor backplane, which are capable of presenting clear cartoon images and videos.