scholarly journals Tunable light emission by exciplex state formation between hybrid halide perovskite and core/shell quantum dots: Implications in advanced LEDs and photovoltaics

2016 ◽  
Vol 2 (1) ◽  
pp. e1501104 ◽  
Author(s):  
Rafael S. Sanchez ◽  
Mauricio Solis de la Fuente ◽  
Isaac Suarez ◽  
Guillermo Muñoz-Matutano ◽  
Juan P. Martinez-Pastor ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Light Emission ◽  
Mixed System ◽  
Core Shell ◽  
Carrier Injection ◽  
Intermediate Band ◽  
Light Emitting ◽  
Exciplex Emission ◽  
Halide Perovskite

We report the first observation of exciplex state electroluminescence due to carrier injection between the hybrid lead halide perovskite (MAPbI3–xClx) and quantum dots (core/shell PbS/CdS). Single layers of perovskite (PS) and quantum dots (QDs) have been produced by solution processing methods, and their photoluminescent properties are compared to those of bilayer samples in both PS/QD and QD/PS configurations. Exciplex emission at lower energies than the band gap of both PS and QD has been detected. The exciplex emission wavelength of this mixed system can be simply tuned by controlling the QD size. Light-emitting diodes (LEDs) have been fabricated using those configurations, which provide light emission with considerably low turn-on potential. The “color” of the LED can also be tuned by controlling the applied bias. The presence of the exciplex state PS and QDs opens up a broad range of possibilities with important implications not only in tunable LEDs but also in the preparation of intermediate band gap photovoltaic devices with the potentiality of surpassing the Shockley-Queisser limit.

scholarly journals Quantum Dots and Applications

Materials ◽  
2020 ◽  
Vol 13 (4) ◽  
pp. 897
Author(s):  
Chang-Yeol Han ◽  
Hyun-Sik Kim ◽  
Heesun Yang
Keyword(s):  
Quantum Dots ◽  
Optical Properties ◽  
Band Gap ◽  
Light Emitting Diodes ◽  
Photovoltaic Cells ◽  
Core Shell ◽  
Special Issue ◽  
High Quality ◽  
Light Emitting ◽  
Size Dependent

It is the unique size-dependent band gap of quantum dots (QDs) that makes them so special in various applications. They have attracted great interest, especially in optoelectronic fields such as light emitting diodes and photovoltaic cells, because their photoluminescent characteristics can be significantly improved via optimization of the processes by which they are synthesized. Control of their core/shell heterostructures is especially important and advantageous. However, a few challenges remain to be overcome before QD-based devices can completely replace current optoelectronic technology. This Special Issue provides detailed guides for synthesis of high-quality QDs and their applications. In terms of fabricating devices, tailoring optical properties of QDs and engineering defects in QD-related interfaces for higher performance remain important issues to be addressed.

scholarly journals Fabrication of a light-emitting device based on the CdS/ZnS spherical quantum dots

2021 ◽  
Vol 17 (1) ◽  
Author(s):  
Kobra Hasanirokh ◽  
Asghar Asgari ◽  
Saber Mohammadi
Keyword(s):  
Quantum Dots ◽  
Current Density ◽  
White Light ◽  
Light Emission ◽  
Blue Emission ◽  
White Light Emission ◽  
Core Shell ◽  
Device Structure ◽  
Light Emitting ◽  
Particle Layer

AbstractIn this work, we focus on the colloidal quantum dot based light-emitting diodes (QD-LEDs) performance. First, we synthesize the spherical QDs with a CdS core that covered with a wider band gap II–VI semiconductor acting as a shell (ZnS). In order to synthesize this nano crystal QDs with structure of CdS/ZnS/CdS/ZnS, we use a reverse micelle process. These four-layer quantum well quantum dots (QWQDs) can generate the white light emission. The positional design of different layers i.e., core/shell QD emitters is a critical factor for white emissive devices. The blue emission generated by CdS core mixes with green/orange components originating from ZnS inner shell and creates an efficiency white light emission. Then, we fabricate a white-QDLED with a device structure of FTO/ ZnO / QD / CBP/ MoO3 / Al films. A thin film of CdS/ZnS/CdS/ZnS QDs is deposited by electrostatically assembled colloidal QD solutions. The experimental results show that the emission spectra of QDs and current density through the LED are controlled by varying the particle sizes. The peaks of absorbance and Photoluminescence (PL) spectrums for core/shell structures get the red shifted as the dot size increases. Furthermore, this QD-LED with a smaller nano particle layer has a higher current density.

Zinc quinolate complex decorated CuInS2/ZnS core/shell quantum dots for white light emission

2017 ◽  
Vol 5 (29) ◽  
pp. 7291-7296 ◽  
Author(s):  
Sabyasachi Pramanik ◽  
Satyapriya Bhandari ◽  
Arun Chattopadhyay
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
Light Emission ◽  
White Light Emission ◽  
Core Shell ◽  
Light Emitting

Formation of a zinc-quinolate complex on the surface of CuInS2/ZnS core shell quantum dots leading to the fabrication of an advanced white light emitting nanocomposite.

Surface Organic Ligands-Passivated Quantum Dots: Toward High-Performance Light-Emitting Diodes with Long Lifetime

2021 ◽  
Author(s):  
Lishuang Wang ◽  
Ying Lv ◽  
Jie Lin ◽  
Jialong Zhao ◽  
Xingyuan Liu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Performance ◽  
Light Emitting Diodes ◽  
Organic Ligands ◽  
Colloidal Quantum Dots ◽  
Core Shell ◽  
Light Emitting ◽  
Long Lifetime

For quantum dots light-emitting diodes (QLEDs), typical colloidal quantum dots (QDs) are usually composed of a core/shell heterostructure which is covered with organic ligands as surface passivated materials to confine...

scholarly journals Encapsulated Passivation of Perovskite Quantum Dot (CsPbBr3) Using a Hot-Melt Adhesive (EVA-TPR) for Enhanced Optical Stability and Efficiency

Crystals ◽  
2021 ◽  
Vol 11 (4) ◽  
pp. 419
Author(s):  
Saradh Prasad ◽  
Mamduh J. Aljaafreh ◽  
Mohamad S. AlSalhi ◽  
Abeer Alshammari
Keyword(s):  
Quantum Dots ◽  
Band Gap ◽  
Surface Defects ◽  
Optoelectronic Devices ◽  
Ethylene Vinyl Acetate ◽  
Light Emitting ◽  
Optical Stability ◽  
Perovskite Quantum Dots ◽  
Polymer Light Emitting Diodes ◽  
Hot Melt

The notable photophysical characteristics of perovskite quantum dots (PQDs) (CsPbBr3) are suitable for optoelectronic devices. However, the performance of PQDs is unstable because of their surface defects. One way to address the instability is to passivate PQDs using different organic (polymers, oligomers, and dendrimers) or inorganic (ZnS, PbS) materials. In this study, we performed steady-state spectroscopic investigations to measure the photoluminescence (PL), absorption (A), transmission (T), and reflectance (R) of perovskite quantum dots (CsPbBr3) and ethylene vinyl acetate/terpene phenol (1%) (EVA-TPR (1%), or EVA) copolymer/perovskite composites in thin films with a thickness of 352 ± 5 nm. EVA is highly transparent because of its large band gap; furthermore, it is inexpensive and easy to process. However, the compatibility between PQDs and EVA should be established; therefore, a series of analyses was performed to compute parameters, such as the band gap, the coefficients of absorbance and extinction, the index of refractivity, and the dielectric constant (real and imaginary parts), from the data obtained from the above investigation. Finally, the optical conductivities of the films were studied. All these analyses showed that the EVA/PQDs were more efficient and stable both physically and optically. Hence, EVA/PQDs could become copolymer/perovskite active materials suitable for optoelectronic devices, such as solar cells and perovskite/polymer light-emitting diodes (PPLEDs).

The Emission Property of Phosphors LEDs Based on ZnCuInS/ZnSe/ZnS Quantum Dots

2014 ◽  
Vol 989-994 ◽  
pp. 623-625
Author(s):  
Ke Bi ◽  
Wen Yan Liu ◽  
Tian Yue Xu ◽  
Tie Qiang Zhang ◽  
Yu Zhang
Keyword(s):  
Quantum Dots ◽  
Photoluminescence Spectrum ◽  
Stokes Shift ◽  
Core Shell ◽  
Photoluminescence Properties ◽  
Red Emission ◽  
Light Emitting ◽  
Quantum Size ◽  
Gan Led ◽  
Photoluminescence Peak

.In this research, ZnCuInS/ZnSe/ZnS quantum dots (QDs) have been studied as an excellent red emitting source for blue GaN LED because of its non-toxic deep red emmission, and large Stokes shift properties. In the paper ZnCuInS/ZnSe/ZnS core/shell quantum dots were prepared with the particle size of 4.5nm. According to the measurement of photoluminescence spectrum emitted by ZnCuInS/ZnSe/ZnS core/shell quantum dots, the emitting peak of 700 nm and the full was achieved as red emitter.It was found that absorption edge and photoluminescence peak shifted to shorter wavelength with decreasing the nanocrystal size due to quantum size effect.Meanwhile, we were prepared ZnCuInS/ZnSe/ZnS core/shell quantum dot light emitting diodes and their photoluminescence properties were studied. After the suitable bias was applied on the films, increasing the ZnCuInS/ZnSe/ZnS QDs concentration in the blue GaN chips, red emission increased with decreasing LED’s blue light.

Amine-Free Synthesis of Cesium Lead Halide Perovskite Quantum Dots for Efficient Light-Emitting Diodes

2016 ◽  
Vol 26 (47) ◽  
pp. 8757-8763 ◽  
Author(s):  
Emre Yassitepe ◽  
Zhenyu Yang ◽  
Oleksandr Voznyy ◽  
Younghoon Kim ◽  
Grant Walters ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Light Emitting Diodes ◽  
Light Emitting ◽  
Perovskite Quantum Dots ◽  
Halide Perovskite ◽  
Lead Halide

scholarly journals Selective carrier injection into patterned arrays of pyramidal quantum dots for entangled photon light-emitting diodes

2016 ◽  
Vol 10 (12) ◽  
pp. 782-787 ◽  
Author(s):  
T. H. Chung ◽  
G. Juska ◽  
S. T. Moroni ◽  
A. Pescaglini ◽  
A. Gocalinska ◽  
...  
Keyword(s):  
Quantum Dots ◽  
Light Emitting Diodes ◽  
Carrier Injection ◽  
Light Emitting

Visible Light Emission from Erbium Doped Yttria Stabilized Zirconia

2003 ◽  
Vol 789 ◽  
Author(s):  
Michael Cross ◽  
Walter Varhue
Keyword(s):  
Band Gap ◽  
Light Emission ◽  
Green Light ◽  
Yttria Stabilized Zirconia ◽  
Stabilized Zirconia ◽  
Rare Earth Ion ◽  
Device Structure ◽  
Insulating Layer ◽  
Light Emitting ◽  
Erbium Doped

ABSTRACT: One of the major shortcomings of silicon (Si) as a semiconductor material is its inability to yield efficient light emission. There has been a continued interest in adding rare earth ion impurities such as erbium (Er) to the Si lattice to act as light emitting centers. The low band gap of Si however has complicated this practice by quenching and absorbing this possible emission. Increasing the band gap of the host has been successfully tried in the case of gallium nitride (GaN) [1] and Si-rich oxide (SRO) [2] alloys. A similar approach has been tried here, where Er oxide (ErOx) nanocrystals have been formed in a yttria stabilized zirconia (YSZ) host deposited on a Si (100) substrate. The YSZ is deposited as a heteroepitaxial, insulating layer on the Si substrate by a reactive sputtering technique. The Er is also incorporated by a sputtering process from a metallic target and its placement in the YSZ host can be easily controlled. The device structure formed is a simple metal contact/insulator/phosphor sandwich. The device has been found to emit visible green light at low bias voltages. The advantage of this material is that it is much more structured than SiO2 which can theoretically lead to higher emission intensity.

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