Bifunctional Molecule Enables High-Quality CsPb(Br/Cl)₃ Nanocrystals for Efficient and Stable Pure-Blue Perovskite Light-Emitting Diodes

The development of pure-blue perovskite light-emitting diodes (PeLEDs) required for displays lags dramatically behind that of PeLEDs with green and red emission. Mixed halide (Br/Cl) perovskite nanocrystals (PeNCs) are commonly used to realize blue emission but are usually accompanied by Cl vacancies and ion migration. In this work, a bifunctional molecule was employed for the synthesis of high-quality CsPb(Br/Cl)3 PeNCs. Trichloro(1H,1H,2H,2H-tridecafluoro-n-octyl)silane (PFTS), of which the Cl– ions function as the Cl-precursors while the F– ions work as the surface passivator, was explored, and the obtained products exhibited a high photoluminescence quantum yield (PLQY) of 87%. Consequently, the LED fabricated with the optimized PeNCs reached an external quantum efficiency of 1.62% and luminance of 482 cd m–2 at the electroluminescence wavelength of 461 nm. Simultaneously, the efficient halide vacancy passivation by PFTS suppressed ion migration and hence dramatically improved the spectral stability of the device.