scholarly journals Strategies to Improve Luminescence Efficiency and Stability of Blue Perovskite Light‐Emitting Devices

Small Science ◽  
2021 ◽  
pp. 2000048
Author(s):  
Xiao-Yan Qian ◽  
Ying-Yi Tang ◽  
Wei Zhou ◽  
Yang Shen ◽  
Ming-Lei Guo ◽  
...  
Keyword(s):  
Light Emitting ◽  
Light Emitting Devices ◽  
Luminescence Efficiency

scholarly journals Bright Alloy CdZnSe/ZnSe QDs with Nonquenching Photoluminescence at High Temperature and Their Application to Light-Emitting Diodes

2019 ◽  
Vol 2019 ◽  
pp. 1-8
Author(s):  
Tingting Zhang ◽  
Xugu Zhang ◽  
Peizhi Yang ◽  
Jinke Bai ◽  
Chun Chang ◽  
...  
Keyword(s):  
Quantum Dots ◽  
High Temperature ◽  
Quantum Yields ◽  
Excellent Performance ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Maximum Current Density ◽  
Luminescence Efficiency ◽  
Maximum Current ◽  
Pl Quenching

Stable luminance properties are essential for light-emitting devices with excellent performance. Thermal photoluminescence (PL) quenching of quantum dots (QDs) under a high temperature resulting from a surface hole or electron traps will lead to unstable and dim brightness. After treating CdZnSe/ZnSe QDs with TBP, which is a well-known passivation reagent of the anions, the excess Se sites on the surface of the QDs were removed and their PL quantum yields (QYs) was improved remarkable. Furthermore, after TBP treatment, the CdZnSe/ZnSe QDs exhibit no quenching phenomena even at a high temperature of 310°C. The electroluminescent light-mitting diodes based on the QDs with TBP treatment also demonstrated satisfied performance with a maximum current density of 1679.6 mA/cm2, a peak luminance of 89500 cd/m2, and the maximum values of EQE and luminescence efficiency are 15% and 14.9 cd/A, respectively. The performance of the fabricated devices can be further improved providing much more in-depth studies on the CdZnSe/ZnSe QDs.

Non-Radiative Competition in the Excitation of Erbium Implanted Silicon Light Emitting Devices

1995 ◽  
Vol 392 ◽  
Author(s):  
T Taskin ◽  
Q Huda ◽  
A Scholes ◽  
J H Evans ◽  
A R Peaker ◽  
...  
Keyword(s):  
Threshold Current ◽  
Threshold Current Density ◽  
Extended Defects ◽  
Cross Sectional ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Radiative Processes ◽  
Luminescence Efficiency ◽  
High Concentrations

AbstractThis paper reports a study of the non-radiative processes competing with the excitation of the erbium ion in layers implanted with high concentrations of erbium and oxygen. These processes reduce the luminescence efficiency of the Si:Er system and dramatically increase the threshold current density calculated to be necessary for an ultimate goal, the Si/Ge:Er LASER. Using cross sectional TEM, photoluminescence as a function of temperature and DLTS, it is demonstrated that a two stage anneal procedure which avoids the formation of extended defects and removes specific deep states is necessary to obtain efficient Er3+ excitation at high erbium concentrations. Comparisons are made with damage resulting from germanium implantation into silicon. The role of multiple stage anneals is discussed in relation to the removal of Shockley-Hall-Read recombination centres

Structural Dependence and Dynamics of White Luminescence in Multilayer Structures for White Organic Light Emitting Devices

2001 ◽  
Vol 708 ◽  
Author(s):  
Shizuo Fujita ◽  
Ken-ichi Uesaka ◽  
Shigeo Fujita
Keyword(s):  
Blue Luminescence ◽  
Multilayer Structures ◽  
Operating Voltage ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Luminescence Efficiency ◽  
White Electroluminescence ◽  
Red Luminescence ◽  
White Luminescence ◽  
Stacking Structure

ABSTRACTWhite electroluminescence (EL) spectra are carefully investigated in terms of the multilayer structures and a rule for designing the white luminescence is discussed. For a simple structure which consists of tris(8-hydroxyquinoline)-aluminum (Alq) and 1,2,3,4,5-pentaphenyl-1,3-cyclopendadiene (PPCP) emitting green and blue luminescence, respectively, as luminescent and electron transport layers, white luminescence appeared if the thickness of each layer was appropriately chosen. The luminescence efficiency was higher in PPCP, and therefore one of the structures effectively emitting white luminescence was designed as PPCP(10 nm)/Alq(40 nm). The 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) was then added to the PPCP/Alq structure intending to enhance red luminescence. We propose the structure where red luminescence is from the DCM as photoluminescence excited by the green and blue luminescence from Alq and PPCP, which was effective, compared to the PPCP/Alq/DCM stacking structure, in avoiding increase of the operating voltage. The importance of designing structures of organic white EL devices based on fundamental optical properties of the constituent layers and on luminescence dynamics is highlighted.

Heterostructures based on nitrides of group III elements: technical processes, properties, and light-emitting devices

2001 ◽  
Vol 171 (8) ◽  
pp. 857 ◽  
Author(s):  
Igor L. Krestnikov ◽  
V.V. Lundin ◽  
A.V. Sakharov ◽  
D.A. Bedarev ◽  
E.E. Zavarin ◽  
...  
Keyword(s):  
Light Emitting ◽  
Group Iii ◽  
Light Emitting Devices

Probing local photophysical properties in perovskite based light-emitting devices

2019 ◽  
Author(s):  
Miguel Anaya ◽  
Kyle Frohna ◽  
Linsong Cui ◽  
Javad Shamsi ◽  
Sam Stranks
Keyword(s):  
Photophysical Properties ◽  
Light Emitting ◽  
Light Emitting Devices

Color Variable Bipolar/AC Light-Emitting Devices Based on Conjugated Polymers

1997 ◽  
Author(s):  
Y. Z. Wang ◽  
D. D. Gebler ◽  
D. K. Fu ◽  
T. M. Swager ◽  
A. J. Epstein
Keyword(s):  
Conjugated Polymers ◽  
Light Emitting ◽  
Light Emitting Devices

scholarly journals Exciton Coupling and Conformational Changes Impacting the Excited State Properties of Metal Organic Frameworks

Molecules ◽  
2020 ◽  
Vol 25 (18) ◽  
pp. 4230
Author(s):  
Andreas Windischbacher ◽  
Luca Steiner ◽  
Ritesh Haldar ◽  
Christof Wöll ◽  
Egbert Zojer ◽  
...  
Keyword(s):  
Conformational Changes ◽  
Photophysical Properties ◽  
Metal Organic Framework ◽  
Metal Organic Frameworks ◽  
Red Shift ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Exciton Coupling ◽  
Metal Organic ◽  
Crystalline Metal

In recent years, the photophysical properties of crystalline metal-organic frameworks (MOFs) have become increasingly relevant for their potential application in light-emitting devices, photovoltaics, nonlinear optics and sensing. The availability of high-quality experimental data for such systems makes them ideally suited for a validation of quantum mechanical simulations, aiming at an in-depth atomistic understanding of photophysical phenomena. Here we present a computational DFT study of the absorption and emission characteristics of a Zn-based surface-anchored metal-organic framework (Zn-SURMOF-2) containing anthracenedibenzoic acid (ADB) as linker. Combining band-structure and cluster-based simulations on ADB chromophores in various conformations and aggregation states, we are able to provide a detailed explanation of the experimentally observed photophysical properties of Zn-ADB SURMOF-2: The unexpected (weak) red-shift of the absorption maxima upon incorporating ADB chromophores into SURMOF-2 can be explained by a combination of excitonic coupling effects with conformational changes of the chromophores already in their ground state. As far as the unusually large red-shift of the emission of Zn-ADB SURMOF-2 is concerned, based on our simulations, we attribute it to a modification of the exciton coupling compared to conventional H-aggregates, which results from a relative slip of the centers of neighboring chromophores upon incorporation in Zn-ADB SURMOF-2.

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