Multistate electrically controlled photoluminescence switching

Abstract

Reversibly fluorescent switchable materials have important applications in the fields of ultrahigh-density optical data storage, molecular switches, logic gates, molecular wires, optical/electronic devices, sensors, bioimaging and so on. Some systems have been developed based on smart luminescent polymers and organic photoswitchable molecules. However, the use of such materials for practical applications is dramatically restricted by their intrinsic drawbacks such as low ON/OFF ratios, irreversibility and poor environmental resistance. An imperative challenge toward real applications is to design and fabricate photoluminescence switching devices with high on/off contrast and fast response time, and especially to obtain multicolored systems, in which the photoluminescence wavelength can be easily tuned in the visible region. Here we report the first inorganic example of a multicolored photoluminescence switching system by controlling the organization of crown-type polyoxometalates (POMs) and CdSe@CdS core-shell quantum dots (QDs) into the layer-by-layer (LBL) nanostructures. The photoluminescence of this system can be switched on and off reversibly upon application of step potentials for different redox states, owing to the energy transfer between reduced POMs and QDs. This system displays a quick response (off 17 s, on 38 s), high on/off contrast ($91%), good cycling performance (the modulation ratio is only decreased by 19% after 200 cycles) and also has the advantage of low power consumption. Furthermore, reversible four-state fluorescence switching is realized by integrating different-sized QDs in one multifunctional system.

New electrofluorochromic polymer bearing oligoaniline, carbazole, and polyhedral oligomeric silsesquioxane: Synthesis and properties

“…The vibration around 1633 cm 21 is attributed to the stretching vibration of carbonyl groups. The stretching vibration of C@C groups in the benzene rings is observed at 1603 cm 21 and 1502 cm 21 . The characteristic stretching vibration of CAN appears at 1309 cm 21 .…”

“…The stretching vibration of C@C groups in the benzene rings is observed at 1603 cm 21 and 1502 cm 21 . The characteristic stretching vibration of CAN appears at 1309 cm 21 . The main asymmetric stretching t SiAOASi mode from POSS shows at 1092 cm 21 .…”

“…The structure of POCP was confirmed through Fourier-transform infrared spectra (FTIR), Nuclear magnetic resonance (NMR) spectra, and gel permeation chromatography (GPC). The FTIR spectrum shows the characteristic absorption bonds around 3328 cm 21 corresponding to the NAH stretching vibration, around 2925 cm 21 and 2848 cm 21 due to the CAH stretching vibrations of alkyl groups. The vibration around 1633 cm 21 is attributed to the stretching vibration of carbonyl groups.…”

“…The characteristic stretching vibration of CAN appears at 1309 cm 21 . The main asymmetric stretching t SiAOASi mode from POSS shows at 1092 cm 21 . In addition, the deformation vibration of POCP is presented at 836 cm 21 , 752 cm 21 , and 642 cm 21 .…”

“…2,3 So far, electrofluorochromic materials can be broadly divided into four types: molecular dyads, [4][5][6] intrinsically switchable fluorophores, 7-9 switchable fluorescent polymers, [10][11][12][13][14][15][16] and switchable fluorescent composites. [17][18][19][20][21][22] Among those, electrofluorochromic polymers are highly desirable for their fast switching speed, facile molecular design and good processability. There are currently a variety of strategies to construct the electrofluorochromic polymers using different electroactive units and fluorescence emission units.…”