Inorganic halide perovskite quantum dots (QDs) suffer from problems related to poor water stability and poor thermal stability. Here we developed a simple strategy to synthesize alkyl phosphate (TDPA) coated CsPbBr QDs by using 1-tetradecylphosphonic acid both as the ligand for the CsPbBr QDs and as the precursor for the formation of alkyl phosphate. These QDs not only retain a high photoluminescence quantum yield (PLQY, 68%) and narrow band emission (FHWM ∼ 22 nm) but also exhibit high stability against water and heat. The relative PL intensity of the QDs was maintained at 75% or 59% after being dispersed in water for 5 h or heated to 375 K (100 °C), respectively. Finally, white light-emitting diodes (WLEDs) with a high luminous efficiency of 63 lm W and a wide color gamut (122% of NTSC) were fabricated by using green-emitting CsPbBr/TDPA QDs and red-emitting KSiF:Mn phosphors as color converters. The luminous efficiency of the WLEDs remained at 90% after working under a relative humidity (RH) of 60% for 15 h, thereby showing promise for use as backlight devices in LCDs.

We present a novel composite strategy to enhance the stability of water-sensitive CsPbBr3 quantum dots (QDs) by embedding the QDs into the super-hydrophobic porous organic polymer frameworks (CPB@SHFW). The CPB@SHFW composites not only preserve a high photoluminescence quantum yield (PLQY ≈ 60%) and narrow band emission (full width at half-maximum ≈ 16 nm) but also inherit the outstanding water-resistant property of SHFW to protect the QDs from hydrolytic degradation. The PLQY of the composites was maintained at 91% (PLQY ≈ 54.3%) of the initial one (PLQY ≈ 60%) after being immersed in water for 31 days. Even after being immersed in water for 6 months, the CPB@SHFW composites still retain a bright green emission. In addition, super-hydrophobic perovskite QD-polymer composites (IPQDs@SHFW) with tunable and bright emission were prepared by using suitable halide salts. A white light-emitting diode (WLED) device was prepared by combining green-emitting CPB@SHFW composites and red-emitting K2SiF6:Mn4+ phosphors with a blue LED chip. The device exhibits a high luminous efficiency of 50 lm/W and a wide color gamut (127% of the National Television System Committee and 95% Rec. 2020). This work provides an alternative approach to solve the challenging stability issue of perovskite QDs; therefore, it has a positive implication for their practical application in liquid crystal display backlights.

This paper studies the exponential stabilization of delayed chaotic neural networks (DCNNs) using what is called periodically intermittent control. An exponential stability criterion for the controlled neural networks, together with its simplified version, is established by using the Lyapunov function and Halanay inequality. The feasible region of control parameters is estimated in a rigorous way. Theoretical results and numerical simulations show that the continuous-time DCNN can be stabilized by intermittent feedback control with nonzero duration.

The microscale composite structure strategy of embedding CsPbBr3 nanocrystals (NCs) in the microscale Cs4PbBr6 matrix (CPB113/CPB416) has successfully demonstrated its ability to resolve the fluorescence quenching of perovskite NCs in the solid agglomeration state due to the loss of quantum confinement. Unfortunately, the controllable synthesis of monodisperse nanoscale composites with bright emission in the solid state remains a great challenge. Here, we present for the first time a novel supersaturated recrystallization process to controllably synthesize monodisperse CPB113/CPB416 composite NCs with bright emission in the solid form, where CsPbBr3 NCs were uniformly embedded in the nano hexagonal Cs4PbBr6 matrix. The existence of 2-methylimidazole (MeIm) not only can control the composition rate of CsPbBr3 to Cs4PbBr6, the size and dispersity of CsPbBr3 in the composite NCs but can also help controllably obtain the monodisperse and hexagonal Cs4PbBr6 matrix. The as-prepared composite structure can effectively prevent CsPbBr3 fluorescence quenching and make the composite NCs have a high photoluminescence quantum yield (PLQY) of 83%. In addition, we obtained tunable blue to red emitting composite NCs by varying the halide salts.

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