Ultrasensitive Temperature Sensing Based on Ligand‐Free Alloyed CsPbCl_xBr_3−x Perovskite Nanocrystals Confined in Hollow Mesoporous Silica with High Density of Halide Vacancies

Abstract

Temperature sensing based on fluorescent semiconductor nanocrystals has recently received immense attention. Enhancing the trap‐facilitated thermal quenching of the fluorescence should be an effective approach to achieve high sensitivity for temperature sensing. Compared with conventional semiconductor nanocrystals, the defect‐tolerant feature of lead halide perovskite nanocrystals (LHP NCs) endows them with high density of defects. Here, hollow mesoporous silica (h‐SiO2) template‐assisted ligand‐free synthesis and halogen manipulation (chloride‐importing) are proposed to fabricate highly defective yet fluorescent CsPbCl1.2Br1.8 NCs confined in h‐SiO2 (CsPbCl1.2Br1.8 NCs@h‐SiO2) for ultrasensitive temperature sensing. The trap barrier heights, exciton–phonon scattering, and trap state filling process in the CsPbCl1.2Br1.8 NCs@h‐SiO2 and CsPbBr3 NCs@h‐SiO2 are studied to illustrate the higher temperature sensitivity of CsPbCl1.2Br1.8 NCs@h‐SiO2 at physiological temperature range. By integrating the thermal‐sensitive CsPbCl1.2Br1.8 NCs@h‐SiO2 and thermal‐insensitive K2SiF6:Mn4+ phosphor into the flexible ethylene–vinyl acetate polymer matrix, ratiometric temperature sensing from 30.0 °C to 45.0 °C is demonstrated with a relative temperature sensitivity up to 13.44% °C−1 at 37.0 °C. The composite film shows high potential as a thermometer for monitoring the body temperature. This work demonstrates the unparalleled temperature sensing performance of LHP NCs and provides new inspiration on switching the defects into advantages in sensing applications.

Large-scale continuous preparation of highly stable α-CsPbI3/m-SiO2 nanocomposites by a microfluidics reactor for solid state lighting application

“…We recently reported stable CsPbBr 3 NCs prepared using mesoporous silicon (m-SiO 2 ), and an in situ growth reaction to prepare CsPbBr 3 @m-SiO 2 nanocomposites, where m-SiO 2 effectively suppresses the self-absorption from the NC powder and improves chemical stability and photoluminescence quantum yield (PLQY). 20 Although there have been some reports recently about ultrastable, repeatable, high-quality perovskite CsPbCl 3 and CsPbBr 3 nanocomposites, [36][37][38] reports on CPI NCs remain limited. One of the primary reasons is that the interaction between I-and oleylammonium leads to the rapid agglomeration of NCs and a phase transition from cubic to orthorhombic.…”

Synergistic Effects of Surface Ligand Engineering and Double Matrices Protecting Enable Ultrastable and Highly Emissive Blue/Cyan Perovskite Nanocrystal Films for Multifunctional Applications

“…Table 5 shows the comparison of optical performance and stability of blue/cyan-emitting perovskite composites in this work and previous reports. [10,13,[46][47][48][49][50][51] In contrast, the as-fabricated SiO 2 @DDAB-CsPbCl 0.8 Br 2.2 /SIS and SiO 2 @DDAB-CsPbCl 2.0 Br 1.0 /SIS films exhibit comparable fluorescence properties, and display significantly improved storage and water stability. Notably, the temperature sensing range of SiO 2 @DDAB-CsPbCl 0.8 Br 2.2 /SIS and SiO 2 @DDAB-CsPbCl 2.0 Br 1.0 /SIS composite film in this work is much wider than that of literatures, as seen in Table S8 (Supporting Information), which indicates their great application potential in the field of temperature sensors.…”

Development of Perovskite Quantum Dots for Two-Dimensional Temperature Sensors

“…Li et al have introduced the CsPbBr 3 QDs into oxyhalide glass, resulting in a satisfying temperature sensitivity. 52 53,54 Nevertheless, none of the other proposed protocols can give a fast 2D measurement of the temperature field with an excellent spatial and temporal resolution at the same time for a temperature range between room temperature and 80 °C.…”

“…Huang et al and Jin et al have encapsulated the QDs in hollow mesoporous silica and polystyrene particles. Their attempts have resulted in two different ultrasensitive temperature sensing mechanisms around 45 °C. , Nevertheless, none of the other proposed protocols can give a fast 2D measurement of the temperature field with an excellent spatial and temporal resolution at the same time for a temperature range between room temperature and 80 °C.…”