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.