scholarly journals Hybrid white light emitting devices (HWLEDs) from organic polymer and PbS nanocrystals by multiple excitons

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Akeel M. Kadim
Keyword(s):  
White Light ◽  
Energy Gap ◽  
Color Temperature ◽  
Hole Injection ◽  
Organic Polymer ◽  
Good Efficiency ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
White Light Generation ◽  
White Luminescence

AbstractHybrid white light-emitting devices (HWLEDs) were fabricated using FTO/PEDOT: PSS/PbS/Alq3/Ni system and synthesized by phase separation process. In the present study, the multiple excitons generation in lead sulfide (PbS) NCs, which is characteristic of PbS NCs, was used to induce an effective and regulated energy transfer to an HWLED. The HWLED consisted of three layers successively deposited on FTO glass substrate; the first layer consisted of poly (3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT: PSS) blended with polymethyl methacrylate (PMMA) organic polymer in the 1:1 ratio, while the second layer consisted of PbS NCs. Finally, above the layer of the PbS NCs, Tris (8-hydroxyquinoline) aluminum (Alq3) layer was deposited. The white light was generated with quite a good efficiency due to the confinement effect that makes the energy gap greater. The characteristics of the current-voltage (I-V) indicate acceptable conditions for the generation of white light by multiple excitons. It was found that the emission levels able to produce white luminescence, classified based on the coordinate system of chromaticity (CIE 1931), are x = 0.31, y = 0.33 while the correlated color temperature (CCT) is about 6250 K. The HWLEDs made from PbS NCs with hole injection from the organic polymer (PEDOT: PSS with PMMA), and electron injection from organic molecules (Alq3) are capable of white light generation.

White Light Generation from Electroluminescence Devices Using TPD:PMMA/QDs/Alq3

2017 ◽  
Vol 15 ◽  
pp. 10-20 ◽  
Author(s):  
Omar A. Ibrahim ◽  
Akeel M. Kadim ◽  
Wasan R. Saleh
Keyword(s):  
White Light ◽  
Energy Gap ◽  
Color Temperature ◽  
Hole Injection ◽  
Organic Polymer ◽  
Broad Emission Band ◽  
White Light Generation ◽  
Ito Glass ◽  
Hybrid Junction ◽  
Light Generation

Quantum dots of CdSe, CdS and ZnS QDs were prepared by chemical reaction and used to fabricate organic quantum dot hybrid junction device. QD-LEDs were fabricated using layers of ITO/TPD: PMMA/CdSe/Alq3, ITO/TPD: PMMA/CdS/Alq3 and ITO/TPD: PMMA/ZnS/Alq3 devices which prepared by phase segregation method. The hybrid white light emitting devices consists, of three-layers deposited successively on the ITO glass substrate; the first layer was of N, N’-bis (3-methylphenyl)-N, N’-bis (phenyl) benzidine (TPD) polymer mixed with polymethyl methacrylate (PMMA) polymers. The second layer was QDs while the third layer was tris (8-hydroxyquinoline) aluminium (Alq3). The results of the optical properties show that the prepared QDs were nanocrystalline with defects formation. The calculated of energy gaps from photoluminescence (PL) spectrometer were 2.38, 2.69 and 3.64 eV for CdSe, CdS and ZnS respectively. The generated white light has acceptable efficiency using confinement effect which makes the energy gap larger, so that the direction of the light sites are toward the center of white light color. The hybrid junction devices (EL devices) were characterized by room temperature PL and electroluminescence (EL). Current-voltage (I–V) characteristics indicate that the output current is good compared to the few voltages ( 8-10.3 V) used which gives acceptable results to get a generation of white light. The EL spectrum reveals a broad emission band covering the range from 350 - 700 nm. The emissions causing this white luminescence were identified depending on the chromaticity coordinates (CIE 1931). The correlated color temperature (CCT) was found to be about 6250, 5310 and 5227K respectively. Fabrication of EL-devices from semiconductors material (CdSe, CdS and ZnS QDs) with hole injection organic polymer (TPD) and electron injection from organic molecules (Alq3) was effective in white light generation

Fabrication of Hybrid QDOLEDs from Core/Shell/Shell QDs and Conductive Organic Polymers

2018 ◽  
Vol 22 ◽  
pp. 11-22 ◽  
Author(s):  
Akeel M. Kadim ◽  
Karrar A. Hammoodi ◽  
Ghufran S. Salih
Keyword(s):  
White Light ◽  
Color Temperature ◽  
Hole Injection ◽  
Organic Polymer ◽  
Core Shell ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Organic Light ◽  
Ito Glass ◽  
Organic Light Emitting Devices

Core/shell/shell of CdSe/CdTe/CdS QDs were prepared by chemical reaction and used to fabricate hybrid quantum organic light emitting devices (QDOLEDs). QDOLEDs were made-up using layers of ITO/PEDOT: PMMA/QDs/Alq3and ITO/PEDOT: PMMA/QDs/Alq3/TPBi devices which prepared by phase segregation method. The hybrid white light emitting devices consists, of four-layers deposited successively on the ITO glass substrate; the first layer was of Poly(3,4-ethylenedioxythiophene) (PEDOT) polymer mixed with polymethyl methacrylate (PMMA) polymers. The second layer was QDs and the third layer was tris (8-hydroxyquinoline) aluminium (Alq3) while the fourth layer was 1,3,5-tri(phenyl-2-benzimi-dazolyl)-benzene (TPBi) electron extraction layer (EEL)The results of the optical properties show that the prepared QDs were nanocrystalline with defects formation. The produced white light has suitable efficiency by confinement effect which creates the energy gap larger, so that the aim of the light sites are toward the center of white light color.The quantum dots organic light emitting devices (QDOLEDs) were characterized by electroluminescence (EL) at room temperature. Current-voltage (I-V) characteristics indicate that the output current is good compared to the few voltages ( 4-6 V) used which gives acceptable results to get a generation of white light. The emissions affecting this white luminescence were detected depending on the chromaticity coordinates (CIE 1931). The correlated color temperature (CCT) was found to be about 6300 and 5290 K. Fabrication of QDLEDs from semiconductors material (CdSe/CdTe/CdS core/shell/shell QDs) with hole injection organic polymer (PEDOT) and electron injection from organic polymer molecules (TPBi) was successful in white light production.

Zinc Selenide Quantum Dots Light Emitting Devices (ZnSe QDs-LEDs) with Different Organic Polymers

2017 ◽  
Vol 18 ◽  
pp. 11-19 ◽  
Author(s):  
Akeel M. Kadim
Keyword(s):  
Quantum Dots ◽  
Zinc Selenide ◽  
White Light ◽  
Color Temperature ◽  
Organic Polymer ◽  
Broad Emission Band ◽  
Light Emitting Devices ◽  
Hybrid Devices ◽  
White Luminescence ◽  
Physical And Chemical

The physical and chemical characterize of quantum dots (QDs) extensively depend upon the optical and morphological factors such as size and shape. The zinc selenide (ZnSe) quantum dots (QDs) have been prepared by chemical method and used to fabricate quantum dot hybrid junction devices with different types of organics polymers. The optical studies illustrate that the band gap value from the photoluminescence (PL) with high intensity of these QDs is found about 3.1 eV. The electroluminescence's (EL) hybrid devices were demonstrated by room temperature PL and electroluminescence (EL). Current-voltage (I–V) characteristics indicate that the output current is good compared to the few voltages (5.5 V) used which gives good results to get a generation of white light. The EL spectrum reveals a broad emission band covering the range from 350 - 700 nm. The emissions producing this white luminescence were recognized depending on the chromaticity coordinates (CIE 1931). The correlated color temperature (CCT) was found to be about 5759, 3500 and 3498 K for ITO/TPD/ZnSe, ITO/PPV/ZnSe and ITO/PEDOT/ZnSe QDs respectively. Fabrication of EL- hybrid devices from semiconductors materials (ZnSe QDs) with holes injection organic polymer (TPD, PPV and PEDOT) was effective in white light generation.

Fabrication of Quantum Dots Light Emitting Device by Using CdTe Quantum Dots and Organic Polymer

2017 ◽  
Vol 50 ◽  
pp. 48-56 ◽  
Author(s):  
Akeel M. Kadim
Keyword(s):  
White Light ◽  
Phase Segregation ◽  
Organic Polymer ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Hybrid Device ◽  
Cdte Qds ◽  
Junction Device ◽  
Ito Glass ◽  
Hybrid Junction

Cadmium telluride CdTe QDs was prepared by chemical reaction and used to fabricate electroluminescence quantum dot hybrid junction device. QD-LED was fabricated using TPD: PMMA/CdTe/Alq3 device which synthesized by phase segregation method. The hybrid white light emitting devices consists, of three-layers deposited successively on the ITO glass substrate; the first layer was of Tetra-Phenyl Diaminobiphenyl (TPD) polymer mixed with polymethyl methacrylate (PMMA) polymers, while the second layer was 0.5wt% of the (CdTe) QDs for hybrid device, whereas the third layer was Tris (8-hydroxyquinoline) aluminium (Alq3). The optical properties of CdTe QDs were considered by UV-Vis. and photoluminescence (PL) spectrometer. The results show that the prepared QDs were nanocrystalline with defects formation. The Eg calculated from PL were 2.25 eV for Cadmium telluride CdTe QDs was prepared by chemical reaction and used to fabricate electroluminescence quantum dot hybrid junction device. QD-LED was fabricated using TPD: PMMA/CdTe/Alq3device which synthesized by phase segregation method. The hybrid white light emitting devices consists, of three-layers deposited successively on the ITO glass substrate; the first layer was of Tetra-Phenyl Diaminobiphenyl (TPD) polymer mixed with polymethyl methacrylate (PMMA) polymers, while the second layer was 0.5wt% of the (CdTe) QDs for hybrid device, whereas the third layer was Tris (8-hydroxyquinoline) aluminium (Alq3). The optical properties of CdTe QDs were measuredby UV-Vis. and photoluminescence (PL) spectrometer. The results show that the prepared QDs were nanocrystalline with defects formation. The Eg calculated from PL were 2.25 eV for CdTe QDs. The generated white light properties with acceptable efficiency using confinement effect that makes the energy gap larger, thus the direction of the light sites are toward the center of white light color. The organic light emitting device (OLED) wasconsidered by room temperature PL and electroluminescence (EL). Current-voltage (I–V) characteristics indicate that the output current is good compared to the few voltage (6 V) used which gives good results to get a generation of white light. The electroluminescence (EL) spectrum of hybrid deviceshows a wide emission band covering the range from 350 - 700 nm. The emissions causing this white luminescence were identified depending on the chromaticity coordinates (CIE 1931) was found (x=0.32, y=0.33). The correlated color temperature (CCT) was found to be about 5886 K. Fabrication of EL-devices from semiconductors material (CdTe QDs) between two layers organic polymer (TPD) and organic molecules (Alq3) were effective in white light generation. The recombination processes and I-V characteristics gives rises to the output current is good compared to the few voltages used which gives good results to become a generation of light.

Electroluminescence Devices from Quantum Dots with TPD Polymer White Light Generation

2017 ◽  
Vol 48 ◽  
pp. 104-113 ◽  
Author(s):  
M.K. Akeel ◽  
Omar A. Ibrahim ◽  
Wasan R. Saleh
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
Color Temperature ◽  
Organic Polymer ◽  
Broad Emission Band ◽  
Output Current ◽  
White Light Generation ◽  
Ito Glass ◽  
Hybrid Junction ◽  
Light Generation

Quantum dots of CdSe, CdS and ZnS QDs were prepared by chemical reaction and used to fabricate organic quantum dot hybrid junction device. QD-LEDs were fabricated using ITO/TPD: PMMA/CdSe/Al, ITO/TPD: PMMA/CdS/Al and ITO/TPD: PMMA/ZnS/Al QDs devices which synthesized by phase segregation method. The hybrid white light emitting devices consists, of two-layers deposited successively on the ITO glass substrate; the first layer was of N, N’-bis (3-methylphenyl)-N, N’-bis (phenyl) benzidine (TPD) polymer mixed with polymethyl methacrylate (PMMA) polymers in ratio 1:1, while the second layer was 0.5wt% from each type of the (CdSe, CdS and ZnS) QDs for each device.The optical properties of QDs were characterized by UV-Vis. and photoluminescence (PL) spectrometer. The results show that the prepared QDs were nanocrystalline with defects formation. The Eg calculated from PL were 2.38, 2.69 and 3.64 eV for CdSe, CdS and ZnS respectively. The generated white light properties with acceptable efficiency using confinement effect that makes the energy gap larger, thus the direction of the light sites are toward the centre of white light color.The hybrid junction devices (EL devices) were characterized by room temperature PL and electroluminescence (EL). Current-voltage (I–V) characteristics indicate that the output current is good compared to the few voltages ( 8-11.5 V) used which gives acceptable results to get a generation of white light. The EL spectrum reveals a broad emission band covering the range from 350 - 700 nm. The emissions causing this white luminescence were identified depending on the chromaticity coordinates (CIE 1931). The correlated color temperature (CCT) was found to be about 5500, 4885 and 3400K respectively. Fabrication of EL-devices from semiconductors material (CdSe, CdS and ZnS QDs) with hole injection organic polymer (TPD) was effective in white light generation. The recombination processes and I-V characteristics gives rises to the output current is good compared to the few voltages used which gives acceptable results to get a generation of white light.

Blue and green double band luminescent carbon quantum dots: Synthesis, origin of photoluminescence, and application in white light-emitting devices

2021 ◽  
Vol 118 (15) ◽  
pp. 153102
Author(s):  
Xifang Chen ◽  
Wenhui Wu ◽  
Wenxia Zhang ◽  
Ziye Wang ◽  
Zhenjin Fu ◽  
...  
Keyword(s):  
Quantum Dots ◽  
White Light ◽  
Carbon Quantum Dots ◽  
Light Emitting ◽  
Light Emitting Devices

scholarly journals Near Unity PLQY and High Stability of Barium Thiocyanate Based All-Inorganic Perovskites and Their Applications in White Light-Emitting Diodes

Photonics ◽  
2021 ◽  
Vol 8 (6) ◽  
pp. 209
Author(s):  
Gopi Chandra Adhikari ◽  
Saroj Thapa ◽  
Yang Yue ◽  
Hongyang Zhu ◽  
Peifen Zhu
Keyword(s):  
White Light ◽  
Large Scale ◽  
Light Emitting Diode ◽  
Photophysical Properties ◽  
Environmental Stability ◽  
Color Temperature ◽  
Ambient Atmosphere ◽  
Light Emitting ◽  
Halide Perovskite ◽  
Lead Halide

All-inorganic lead halide perovskite (CsPbX3) nanocrystals (NCs) have emerged as a highly promising new generation of light emitters due to their extraordinary photophysical properties. However, the performance of these semiconducting NCs is undermined due to the inherent toxicity of lead and long-term environmental stability. Here, we report the addition of B-site cation and X-site anion (pseudo-halide) concurrently using Ba(SCN)2 (≤50%) in CsPbX3 NCs to reduce the lead and improve the photophysical properties and stability. The as-grown particles demonstrated an analogous structure with an almost identical lattice constant and a fluctuation of particle size without altering the morphology of particles. Photoluminescence quantum yield is enhanced up to near unity (~98%) by taking advantage of concomitant doping at the B- and X-site of the structure. Benefitted from the defect reductions and stronger bonding interaction between Pb2+ and SCN− ions, Ba(SCN)2-based NCs exhibit improved stability towards air and moisture compared to the host NCs. The doped NCs retain higher PLQY (as high as seven times) compared to the host NCs) when stored in an ambient atmosphere for more than 176 days. A novel 3D-printed multiplex color conversion layer was used to fabricate a white light-emitting diode (LED). The obtained white light shows a correlated color temperature of 6764 K, a color rendering index of 87, and luminous efficacy of radiation of 333 lm/W. In summary, this work proposes a facile route to treat sensitive lead halide perovskite NCs and to fabricate LEDs by using a low-cost large-scale 3-D printing method, which would serve as a foundation for fabricating high-quality optoelectronic devices for near future lighting technologies.

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