Spectrally stable and efficient pure-blue light-emitting diodes based on CsPb(Br/Cl)3 nanocrystals with surface passivation by organic sulfonate

Despite rapid development of perovskite nanocrystal (PeNC) light-emitting diodes (LEDs), it remains challenging to achieve efficient and stable blue PeLEDs, especially for pure-blue PeLEDs required for displays. Mixed halide CsPb(Br/Cl)3 NC is a common strategy to achieve pure-blue emission, but suffers from low photoluminescence quantum yield (PLQY) and spectra instability. Here, a facile approach for the synthesis of high-quality pure-blue emitting CsPb(Br/Cl)3 NCs is reported by introducing an organic sulfonate, phenyl trifluoromethanesulfonate (PTFMS), which works as an efficient surface passivator. As a result, the optimized PeNCs achieve a high PLQY of 85% and enhanced conductivity. Furthermore, the LED based on the optimized PeNCs is developed with pure -blue emission at 469 nm, which yields an external quantum efficiency (EQE) of 1.20% and luminance of 355 cd m- 2. More impressively, the device shows excellent spectra and operation stability under voltage bias, resulting from the suppressed ion migration channels by efficient defect passivation.