TiO₂/CsPbBr₃ Quantum Dots Coupled with Polyoxometalate Redox Clusters for Photoswitches

Abstract

Lead-halide perovskite quantum dots (QDs) have been intensively studied, owing to their excellent optical properties. Herein, the photoluminescence (PL) emission of perovskite QDs was controlled by coupling them with a polyoxometalate (POM) redox cluster to develop photoswitches that undergo changes in optical properties in response to light stimulus. CsPbBr 3 QDs were coated with a TiO 2 layer, and photoinduced electron transfer (PET) from the TiO 2 /CsPbBr 3 QDs to (Bu 4 N) 4 [W 10 O 32 ] (tetrakis(tetrabutylammonium)decatungstate) under visible-light irradiation was examined. UV−vis absorbance, PL emission, and PL lifetime measurements indicated that efficient PET from the QDs to the POM took place under visible-light irradiation, thereby quenching the PL emission. PET also led to the generation of one-electron reduced POM (POM − ). The PL quenching proceeded via PET from QDs to POM, POM − formation, and PET to POM − . POM − was easily oxidized on exposure to atmospheric oxygen, leading to the restoration of the PL. The PL emission could be repeatedly quenched and restored by visiblelight irradiation and oxygen introduction, respectively. The results demonstrate the promising utility of the QD/POM system as photoswitches that can be used for super-resolution imaging, photomemory, fluorescent patterning, and bioimaging.

TiO2-Coated CsPbI3 Quantum Dots Coupled with Polyoxometalates for On/Off Fluorescent Photoswitches

“…TBADT was synthesized by the method reported in the previous literature . CsPbBr x I 3– x QDs were synthesized by the hot injection method .…”

“…The TEM elemental mapping images were taken on a Tecnai F20 (FEI) operated by 200 kV. For other characterizations such as DLS, UV–vis, PL, PL decay analysis, and ζ potential measurements, the details were reported in a previous paper …”

“…The On/Off switching of the sharp and bright emission from perovskite QDs is advantageous for bioimaging and display applications. We also attained reversible PL modulation using TiO 2 /CsPbBr 3 QDs coupled with polyoxometalate (POM) as an electron acceptor . PET occurred from QDs to POM through a TiO 2 layer on the surface under visible light irradiation, resulting in the reduction of POM, and the PET was followed by PL quenching.…”

“…We also attained reversible PL modulation using TiO electron acceptor. 38 PET occurred from QDs to POM through a TiO 2 layer on the surface under visible light irradiation, resulting in the reduction of POM, and the PET was followed by PL quenching. The PL emission was recovered by air oxidation of the reduced POM, which allowed for the On/Off PL switching upon alternate visible light irradiation and air oxidation.…”

Phase Regulation of CsPb2Br5/CsPbBr3 Perovskite Nanocrystals by Doping with Divalent Cations: Implications for Optoelectronic Devices with Enhanced Stability and Reduced Toxicity

“…Recently, all-inorganic lead halide perovskite nanocrystals (NCs) have attracted much attention due to their superlative optoelectronic properties including the wide color gamut, , excellent photoluminescence quantum yields (PLQYs), high exciton binding energy and defect tolerance, tunable wavelength, and narrow full-width at half-maximum (FWHM). , As a result, all-inorganic Cs-Pb-X perovskite materials (X stands for Cl, Br, and I) are widely used in optoelectronic devices, such as photovoltaic devices and light-emitting diodes (LEDs) . Despite the fact that the lead-based materials show extensive application prospects, their toxicity and stability are still unresolved, seriously hindering their further commercial development .…”