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

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journal contribution
posted on 29.10.2020, 16:23 authored by Azzah Dyah Pramata, Yuji Akaishi, Koki Sadowara, Yui Mokuge, Naohiro Kodama, Manami Shimoyoshi, Tetsuya Kida
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. CsPbBr3 QDs were coated with a TiO2 layer, and photoinduced electron transfer (PET) from the TiO2/CsPbBr3 QDs to (Bu4N)4[W10O32] (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 visible-light 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.