In Situ Growth Mechanism of CsPbX₃ (X = Cl, Br, and I) Quantum Dots in an Amorphous Oxide Matrix

Abstract

Oxide glass matrix embedding is an effective way to improve the stability of halide quantum dots (QDs). However, the in situ growth mechanism of halide perovskite QDs in an amorphous matrix has not been clarified. In this work, the growth process of halide QDs in an amorphous oxide matrix was successfully elucidated via in situ spectroscopy, analytical electron microscopy, and the X-ray scattering/diffraction technique. The results showed that the in situ growth mechanism of the halide QDs in the amorphous oxide matrix was different from that of traditional glassceramics, which was more like a halide nanoglass-based phase transition process. Typically, a complex multiphase (halide nanoglass, CsPb 2 X 5 , and CsPbX 3 ) transition existed in the amorphous oxide matrix, and the obtained CsPbX 3 QD glass showed a halide multiphase coexisting microstructure. More importantly, the crystallization process from the halide nanoglass to QDs can be induced by known ways, including mechanical force, hydration, and heat treatment. The clarified in situ growth mechanism may pave the way toward the development of high-efficiency halide perovskite QD-embedded amorphous materials and optoelectronic devices.

Self‐Straining Nanocrystals Strategy: Temperature and Pressure Co‐Induced Phase Transitions of CsPbBr3 in Amorphous Matrices

“…In situ growth process of CsPbBr 3 NCs in amorphous matrices takes place at high temperatures (580 K for GC‐CsPbBr 3 , and 348 K for P‐CsPbBr 3 ), which depends on the distinct growth mechanism of CsPbBr 3 NCs in different amorphous matrices. [ 24,25 ] Owing to the thermal expansion coefficient of the borosilicate glass [ 26 ] being significantly lower than that of CsPbBr 3 NCs (Table S1, Supporting Information), the shrinkage of NCs is restricted by the glass matrix in the cooling process. In contrast, the thermal expansion coefficient of PMMA (60‐80 × 10 –6 K –1 ) [ 27 ] is higher than that of CsPbBr 3 NCs, the shrinkage trend of NCs is intensified by PMMA in the cooling process.…”

“…In addition, the size of the NCs in an amorphous matrix can be controlled by changing the heat treatment conditions [ 42 ] or the ultrafast laser parameters. [ 25b,43 ] The local pressure (positive or negative) and operating temperature can be regulated by designing the composition of the multicomponent glass [ 44 ] (silicate, borate, phosphate, tellurate, etc.) or changing the type of the polymer matrix [ 2c,45 ] (PMMA, metal–organic frameworks, etc.).…”

Unique properties and potential of glass-ceramics

“…QDs exhibit phase transitions and formed via complicated crystallization mechanisms depending on the temperature and pressure. 55) QDs have been attracting much attention because of their excellent luminescence properties based on quantum well structures, and when precipitated in glass, transparent bulk materials with high chemical corrosion resistance and safety can be obtained. They are more durable than other matrix such as resins and solgel films and have the advantage of being less prone to QDs aggregation.…”

Reversible Phase Segregation and Amorphization of Mixed-Halide Perovskite Nanocrystals in Glass Matrices

“…There is still no observable phase segregation of mixed-halide perovskite NCs in glass matrices at 350 K (Figure S2b), even though the excitation power density we used is much higher than the previous report. , Notably, the PL intensity of GC-ClBr underwent a slight increase after laser irradiation at 350 K, while the PL intensity of GC-BrI did not show any change (Figure , parts b and c). The PL enhancement of GC-ClBr indicates that there is a possibility of temperature/irradiation-induced growth of mixed-halide perovskite NCs in the glass matrix . Generally, the Br-rich mixed-halide perovskite easily undergoes phase segregation when excited with above-bandgap steady-state illumination. , However, CsPbBr 1.92 I 1.08 NCs in the glass matrix shows excellent stability, even better than CsPbCl 2.04 Br 0.96 NCs with a CsPbCl 3 structure.…”

“…The PL enhancement of GC-ClBr indicates that there is a possibility of temperature/irradiationinduced growth of mixed-halide perovskite NCs in the glass matrix. 42 Generally, the Br-rich mixed-halide perovskite easily undergoes phase segregation when excited with above-bandgap steady-state illumination. 43,44 However, CsPbBr 1.92 I 1.08 NCs in the glass matrix shows excellent stability, even better than CsPbCl 2.04 Br 0.96 NCs with a CsPbCl 3 structure.…”