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Perovskite Quantum Dots (QDs) promise to deliver over 90% of Rec2020 color representation, the highest for RoHS compliant LCD displays. In this study, we strive to demonstrate the performance of LCD displays using QDot green emitt...
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Perovskite Quantum Dots (QDs) promise to deliver over 90% of Rec2020 color representation, the highest for RoHS compliant LCD displays. In this study, we strive to demonstrate the performance of LCD displays using QDot green emitting Perovskite QDs with various backlight architectures. Using different blue and red light sources, we fabricated four types of LCD display, which showed contrasting Rec2020 color gamut from 80 to 86% and brightness from 1000 to 2000 nits. With these impressive metrics, Perovskite Quantum Dots paves the way for mass adoption of the technology in the display field.
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Fully inorganic lead halide perovskite nanocrystals (NCs) are of interest for photovoltaic and light emitting devices due to optoelectronic properties. Understanding the surface chemistry of these materials is of importance as sur...
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Fully inorganic lead halide perovskite nanocrystals (NCs) are of interest for photovoltaic and light emitting devices due to optoelectronic properties. Understanding the surface chemistry of these materials is of importance as surface defects can introduce trap-states which reduce their functionality. Here we use Density Functional Theory (DFT) to model surface defects introduced by Pb2+ on a CsPbBr3 NC atomistic model. Two types of defects are studied: (i) an under-coordinated Pb2+ surface atom and (ii) Pb2+ atomic or molecular adsorbents to the NC surface. From the DFT calculations we compute the density of states (DOS) and absorption spectra of the defect models to the pristine fully-passivated NC model. We observe that for the low surface defect regime explored here that neither (i) or (ii) produce trap-states inside of the bandgap and exhibit bright optical absorption for the lowest energy transition. From the models studied, it was found that the Pb2+ atomic absorbent provides broadening of the conduction band edge, which implies chemisorption of Pb2+ to the NC surface. At higher defect densities it would be expected that Pb2+ atomic absorbents would introduce trap-states and degrade the opto-electronic properties of these materials.
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Herein, we first prepared polychromatic self-crystallized CsPb(Cl/Br/I)(3) perovskite nanocrystalline (PN) borosilicate glass by the high-temperature melting method. Then, the PN glass is exposed to frequent mechanical ball millin...
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Herein, we first prepared polychromatic self-crystallized CsPb(Cl/Br/I)(3) perovskite nanocrystalline (PN) borosilicate glass by the high-temperature melting method. Then, the PN glass is exposed to frequent mechanical ball milling. Due to the high-energy mechanical force, the microstructure changes in borosilicate glass such as topological structure, chemical short-range order, and atomic rearrangement lead to the secondary crystallization of PN on the glass surface. Hence, the photoluminescence quantum yield (PLQY) of CsPbBr3 PN glass has enhanced 120 times and that of CsPbBrI2 PN glass has enhanced 74 times. Moreover, the prepared highly luminescent CsPbBr3 PN glass has extremely large exciton binding energy (468 meV), which shows good thermal stability. Finally, by embedding the prepared PN glass powder in the polydimethylsiloxane matrix, multicolor luminescent flexible films are constructed, presenting application prospects in the flexible display field. This work deepens the understanding of how the microstructure change in glass influences the crystallization behavior of PN and resolves the challenge that PN glass cannot have high PLQY and stability at the same time.
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To improve the photoluminescence quantum yield(PL QY)and the environmental stability of the CsPbCl3 quantum dots(QDs), the Mn doping strategy has been applied first. The substitute of Mn~(2+)can reduce the toxicity of the lead ele...
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To improve the photoluminescence quantum yield(PL QY)and the environmental stability of the CsPbCl3 quantum dots(QDs), the Mn doping strategy has been applied first. The substitute of Mn~(2+)can reduce the toxicity of the lead element firstly, and then slightly enhance the stability of QDs. Increasing the nominal content of Mn, the longtime duration of the intrinsic excitation peak is significantly improved;and at a higher nominal content, a wide red emission by the d-d transition of Mn~(2+)is introduced, the overall PL QY of CsPbCl3 QDs increases to 54.32%. Secondly, to further prevent the penetration of oxygen and water, the Mn-doped CsPbCl3@SiO2 nano-composite with a physical coating shell was synthesized by the hydrolysis of aminopropyltriethoxysilane. The investigation on the PL spectrum within hours shows that the relative peak intensity maintains 74% of the initial intensity and the shift of peak position is also inhibited. Finally, the nano-composite materials were fabricated into white light-emitting devices(WLED), under the illumination of a commercial GaN chip, the device shows a good Commission Internationale de lEclairage(CIE)color coordination of(0.31,0.35). As a result, the obtained Mn-doped CsPbCl3@SiO2 QDs have excellent optical properties and good stability under aqueous and polar solvent environments. Therefore, this doping and coating method could pave the way for future applications in illumination and display fields.
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With the advent of artificial intelligence (AI) and the Internet of Things (IoT), the development of advanced printable synaptic devices has exhibited significant improvements, especially in facile-processed artificial neural netw...
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With the advent of artificial intelligence (AI) and the Internet of Things (IoT), the development of advanced printable synaptic devices has exhibited significant improvements, especially in facile-processed artificial neural networks with versatile information storage and neuromorphic computational capabilities. This enables the further development of the skin-like sensor and information processing systems. Here, we propose a multifunctional synaptic transistor based on a ternary organic semiconductor (OSC)-polymer-inorganic perovskite quantum dot (IPQD) photosensitive layer. Due to the dual optics-absorption functions of the OSCs and IPQDs, the synaptic device demonstrates the lowest power consumption (-0.11 fJ) and significant optically synaptic-like behavior with tunable short-term and long-term neuroplasticity. By adding polymer, the device stability and printability of the ternary solution for printable devices are improved. We further characterize the properties of the synaptic device, the learning-forgetting behavior, Morse code information processing and the pattern recognition capability tested on the MNIST dataset are demonstrated. Our results open the new pathway for skin-like bioinspired multifunctional information processing paradigms.
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In recent decades, quantum dots (QDs) with tunable bandgap, large absorption coefficient, high quantum yield, multiexciton effect, and easy solution processing have unparalleled advantages in photoelectric conversion. Optoelectron...
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In recent decades, quantum dots (QDs) with tunable bandgap, large absorption coefficient, high quantum yield, multiexciton effect, and easy solution processing have unparalleled advantages in photoelectric conversion. Optoelectronic devices based on QDs of different composition have made great progress. However, there is still a lack of reviews on comparing the optoelectronic application level of semiconductor quantum dots (SQDs), perovskite quantum dots (PQDs), and carbon quantum dots (CDs), and also rarely providing a comprehensive summary of photocatalysis. First, this review almost completely summarizes advantages and disadvantages of common synthesis methods for QDs, especially pointing out the importance of optimization strategies for preparing high-quality QDs such as ligand engineering, ion exchange, and purification separation. Then, compositions of SQD, PQD, CD, and corresponding optoelectronic properties are introduced, respectively. Next, the strengths and weaknesses of the four QDs structures are compared in detail. Finally, the flourishing development in various optoelectronic applications is separately demonstrated, and development degree of SQDs, PQDs, and CDs is compared to discover the most suitable application scenarios for each. On these bases, bottlenecks and opportunities are also put forwarded, hoping to stimulate more breakthroughs in this field.
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Hybrid organic-inorganic perovskites are a new class of photoluminescent and low-cost nanomaterials. Chemical transformation using less-toxic elements under ambient reaction conditions has emerged as a major issue due to pressures...
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Hybrid organic-inorganic perovskites are a new class of photoluminescent and low-cost nanomaterials. Chemical transformation using less-toxic elements under ambient reaction conditions has emerged as a major issue due to pressures on environment and human health. Herein, the synthesis of copper-incorporated CH3NH3Pb1-xCuxBr3 based on a ligand-assisted reprecipitation (LARP) technique has been reported. The achieved quantum dots have an average size of 8 nm and the existence of copper has been verified by morphological studies. The nanoscale particles exhibited strong blue luminescence upon the excitation at 370 nm. The replacement by Cu2+ resulted in emission evolution from 468 to 513 nm and the photophysical properties were discussed. This study will open a new approach to control the fluorescence of perovskite-type quantum dots, which will extend its application in different areas. (C) 2018 Elsevier B.V. All rights reserved.
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Having suffered from intrinsic structural lability, perovskite quantum dots (PQDs) are extremely unstable under high-temperature and moisture conditions, which have greatly limited their applications. In this work, we propose a no...
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Having suffered from intrinsic structural lability, perovskite quantum dots (PQDs) are extremely unstable under high-temperature and moisture conditions, which have greatly limited their applications. In this work, we propose a novel method to synthesize ultrastable carbon quantum dots (CQDs)-doped methylamine (MA) lead bromide PQDs with SiO2 encapsulation (CQDs-MAPbBr(3)@SiO2). The kernel CQDs-MAPbBr(3) is formed by the interaction of carboxyl-rich CQDs with MAPbBr(3) via H-bond, which greatly improves the thermal stability of CQDs-MAPbBr(3). Furthermore, highly compact SiO2 encapsulates the proposed CQDs-MAPbBr(3) via a facile in situ growth strategy, which effectively enhances the water resistance and air stability of CQDs-MAPbBr(3)@SiO2. As a result, the proposed nanomaterial shows extremely high water stability in aqueous solution for over 9 months and ideal thermal stability with strong fluorescence (FL) emission after 150 degrees C annealing. Based on the superior stability and ultrahigh FL efficiency of this proposed nanomaterial, a primary sensing method for ion (Ag+ and Zn2+) FL detection has been developed and the mechanism of PQDs-based ion determination has also been discussed, thus exhibiting the potential applications of CQDs-MAPbBr(3)@SiO2 in the area of FL assay and environment monitoring.
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For the first time, the synthesis, luminescent and structural properties of stable perovskite-type (Cs1?xRbx)4PbBr6 (R = Cs, Rb) nanocrystals are shown. In the absence of rubidium, Cs4PbBr6 and CsPbBr3 perovskite crystals precipit...
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For the first time, the synthesis, luminescent and structural properties of stable perovskite-type (Cs1?xRbx)4PbBr6 (R = Cs, Rb) nanocrystals are shown. In the absence of rubidium, Cs4PbBr6 and CsPbBr3 perovskite crystals precipitate in the ZnO-Na2O-B2O3-GeO2 glass matrix. With ascending rubidium content, the precipitation of (Cs,Rb)4PbBr6 nanocrystals is replaced by the Rb4PbBr6 nanocrystals nucleation. Nucleated nanocrystals exhibit an intense green luminescence. With an increase of the rubidium content, the luminescence maximum shifts to the blue region, the luminescence quantum yield increases from 28 to 51%, and the average decay time increases from 2 to 8 ns. Several assumptions have been made about the nature of the green luminescence of perovskite-like Cs4PbBr6 and (Cs,Rb)4PbBr6 crystals in glasses. It is concluded that the most probable cause is the impurity inclusions of CsPbBr3 and (Cs,Rb)PbBr3 crystals.
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Organometallic lead halide perovskites have been studied extensively owing to their excellent photophysical properties and have been successfully applied to solar-driven chemistry and optoelectronic devices. Dimensionally confined...
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Organometallic lead halide perovskites have been studied extensively owing to their excellent photophysical properties and have been successfully applied to solar-driven chemistry and optoelectronic devices. Dimensionally confined perovskite quantum dots (PQDs) have demonstrated outstanding photoluminescence quantum yields, detailed band gap tunability, wide color gamut, and favorable radiative recombination processes. These characteristics expand the versatility of PQDs. Various efforts have been made to increase their stability. The introduction of a core-shell structure increased the stability of PQDs, and they were successfully applied to light-emitting diodes. Recently, our group demonstrated the potential of PQDs to promote photocatalytic degradation of carcinogens. However, further studies on the detailed interactions between PQDs and their surroundings are necessary to utilize them in practice. This study investigated the impact of surrounding solvents on the material/photophysical properties of PQDs and statistically observed the photoinduced charge transfer from PQDs to transparent conducting oxides. The findings of this study could be used to advance solar-driven chemistry and optoelectronic devices and to promote the utilization of PQDs in renewable energy applications.
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