Highly Efficient and Water‐Stable Lead Halide Perovskite Quantum Dots Using Superhydrophobic Aerogel Inorganic Matrix for White Light‐Emitting Diodes

Abstract

hence have drawn a lot of attention as down-conversion materials for white lightemitting diodes (WLEDs). [7][8][9][10] For practical applications, the cost-effectiveness, the optical performance, and the stability of PQDs should be further improved. [4] Particularly, PQDs suffer from low chemical and optical stabilities, resulting in their fast degradation under exposure to moisture, heat, and light irradiance. [11,12] Accordingly, PQDs exhibit much lower stability than conventional rare-earth-based phosphor materials. [13,14] Current research efforts therefore aim at enhancing the stability of PQDs by covering them in inorganic materials, including CdS, [15] zeolite, [16,17] glass, [18,19] CaF 2 , [20] Al 2 O 3 , [21][22][23] SiO 2 , [24][25][26][27][28][29] and TiO 2 . [30] Generally, the protective shells of PQDs are prepared using these inorganic materials by in situ synthesis. While protected PQDs with high chemical, thermal, and irradiation stabilities have been obtained, [28] the water stability of PQDs prepared with these inorganic shells still indicate a lot of room for improvement. For instance, the PL intensity of CaF 2 shell-integrated green PQDs reduces to <50% after a water-resistance test of ≈40 h. [20] Consequently, and until now, PQDs with high water stability are achieved by embedding them in enclosed organic polymer and glass matrices. [18,19,[31][32][33][34][35][36][37][38][39] The hydrophobic surface and dense polymer chains of the matrix can effectively protect the PQDs from the external environment, considerably enhancing their At present, most of lead halide perovskite quantum dots (PQDs) embedded in an enclosed organic polymer or glass matrix can achieve high water stability, yet this limits their subsequent integration with light-emitting diodes (LEDs) and other functional materials. Herein, a postadsorption process using superhydrophobic aerogel inorganic matrix (S-AIM) with open structures is presented to enhance water stability of PQDs and compose newfunctions to them such as magnetism. The CsPbBr 3 PQDs integrated with the S-AIM (AeroPQDs) exhibit a high relative photoluminescence quantum yield (PLQY, 75.6%) of 90.9% compared to pristine PQDs (PLQY, 83.2%). They preserve their initial PL intensity after 11 days of soaking in water and achieve a high relative PLQY stability (50.5%) after soaking for 3.5 months. The hydrophobic (rough) surface of the matrix, its pores with a well-matched mean diameter that promotes the homogeneous integration of PQDs and hinders the penetration of water as well as the oleophylic functional groups covering the surface of these pores are the three factors responsible for the high water stability. Finally, AeroPQDs are easily integrated with other functional nanomaterials, such as Fe 3 O 4 nanoparticles for magnetic manipulation, due to their open structure.

Review of blue perovskite light emitting diodes with optimization strategies for perovskite film and device structure

“…As direct bandgap semiconductors, perovskites are also an ideal light emitting material with excellent optoelectronic properties, in-cluding tunable bandgap, high color purity, wide color gamut, and high photoluminescence quantum yield (PLQY). Moreover, their bi-polar injection property allows them to be not only down-conversion materials 9,10 , but also be used in electroluminescent (EL) light emitting diodes 11−13 . Therefore, it is convincing that perovskite light emitting diodes (PeLEDs) have great potential in the fields of lighting and high-end display.…”

Surface Passivation Strategies for Improving Photoluminescence and Stability of Cesium Lead Halide Perovskite Nanocrystals

“…[43] Additionally, it has been proved that doping of sodium to protect CsPb(Br/I) 3 perovskite NCs during encapsulation with Al 2 O 3 to form Na: CsPb(Br/I) 3 @Al 2 O 3 nanocomposites makes them less vulnerable to moisture and light exposure. [44] So far, many approaches have been developed to attain high stability and photoluminescence of CsPbX 3 perovskite NCs like surface passivation, [45][46][47][48] metal doping, [35,36,38,49] modified synthesis procedures, [17,18,50,51] core-shell, [43,44,52] encapsulation, [42,53,54] etc (See Figure 2). These methods are very diverse and their outcomes are much varied.…”

In Situ Green Synthesis of Ni‐Doped CsPbBr3@SiO2 Composites with Superior Stability for Fabrication of White Light‐Emitting Diodes

“…[42][43][44][45] This method is quite inefficient and difficult to obtain monodispersed NPs; 2) the PNCs are loaded into mesoporous silica nanoparticles (MSN) through the mechanical process or in situ methods. [46][47][48][49][50][51] This strategy is also executed in nonpolar solvents, and the obtained composites show limited stability since the MSN protector is still accessible to the external moisture and ions which are detrimental to PNCs.…”