Blue-emitting bis-tridentate Ir(iii) phosphors: OLED performances vs. substituent effects

2018 ◽  
Vol 6 (39) ◽  
pp. 10486-10496 ◽  
Author(s):  
Hsin-Hung Kuo ◽  
Ling-Yang Hsu ◽  
Jen-Yung Tso ◽  
Wen-Yi Hung ◽  
Shih-Hung Liu ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Radiative Decay ◽  
Substituent Effects ◽  
Decay Lifetime

Dependence of external quantum efficiency (EQE) and radiative decay lifetime of blue-emitting OLED is established with photostable, bis-tridentate Ir(iii) emitters, giving max. EQE and luminescence of 12.2% and 18 980 cd m−2, and with CIEx,y coordinates between (0.16, 0.22) and (0.17, 0.27).

Demonstration of ultra-small (0.2%) for mini-displays

2020 ◽  
Vol 14 (1) ◽  
pp. 011004
Author(s):  
Shubhra S. Pasayat ◽  
Chirag Gupta ◽  
Matthew S. Wong ◽  
Ryan Ley ◽  
Michael J. Gordon ◽  
...  
Keyword(s):  
Quantum Efficiency ◽  
External Quantum Efficiency

scholarly journals Phenylalkylammonium passivation enables perovskite light emitting diodes with record high-radiance operational lifetime: the chain length matters

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yuwei Guo ◽  
Sofia Apergi ◽  
Nan Li ◽  
Mengyu Chen ◽  
Chunyang Yin ◽  
...  
Keyword(s):  
Chain Length ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Light Emitting Diodes ◽  
Surface Defects ◽  
Theoretical Modelling ◽  
Ion Migration ◽  
Light Emitting ◽  
Operational Lifetime ◽  
Chain Lengths

AbstractPerovskite light emitting diodes suffer from poor operational stability, exhibiting a rapid decay of external quantum efficiency within minutes to hours after turn-on. To address this issue, we explore surface treatment of perovskite films with phenylalkylammonium iodide molecules of varying alkyl chain lengths. Combining experimental characterization and theoretical modelling, we show that these molecules stabilize the perovskite through suppression of iodide ion migration. The stabilization effect is enhanced with increasing chain length due to the stronger binding of the molecules with the perovskite surface, as well as the increased steric hindrance to reconfiguration for accommodating ion migration. The passivation also reduces the surface defects, resulting in a high radiance and delayed roll-off of external quantum efficiency. Using the optimized passivation molecule, phenylpropylammonium iodide, we achieve devices with an efficiency of 17.5%, a radiance of 1282.8 W sr−1 m−2 and a record T50 half-lifetime of 130 h under 100 mA cm−2.

Simulation and modeling of the influence of temperature on CdS/CdTe thin film solar cell

2019 ◽  
Vol 87 (3) ◽  
pp. 30101 ◽  
Author(s):  
Abdel-baset H. Mekky
Keyword(s):  
Thin Film ◽  
Solar Cell ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Influence Of Temperature ◽  
Cdte Solar Cell ◽  
Cell Parameters ◽  
Current Voltage ◽  
Capacitance Voltage ◽  
Influence Of Temperature On

Semiconductor materials cadmium sulfide (CdS) and cadmium telluride (CdTe) are employed in the fabrication of thin film solar cells of relatively excessive power conversion efficiency and low producing price. Simulations of thin film CdS/CdTe solar cell were carried out using SCAPS-1D. The influence of temperature field on the variation of CdTe solar cell parameters such as current–voltage, capacitance–voltage characteristics and the external quantum efficiency was investigated theoretically. For use temperatures, one obtains the external quantum efficiency has the same profiles. However, the effect of the temperature on the Mott-Schottky curves is slightly noted by variations on the characteristics. This conclusion can be used by solar cell manufacturers to improve the solar cell parameters with the biggest possible gain in device performance.

scholarly journals Enhancing sub-bandgap external quantum efficiency by photomultiplication for narrowband organic near-infrared photodetectors

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Jonas Kublitski ◽  
Axel Fischer ◽  
Shen Xing ◽  
Lukasz Baisinger ◽  
Eva Bittrich ◽  
...  
Keyword(s):  
Charge Transfer ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Near Infrared ◽  
Optical Cavity ◽  
Hole Injection ◽  
Visible Range ◽  
Absorption Region ◽  
Electromagnetic Signals ◽  
Organic Photodetectors

AbstractDetection of electromagnetic signals for applications such as health, product quality monitoring or astronomy requires highly responsive and wavelength selective devices. Photomultiplication-type organic photodetectors have been shown to achieve high quantum efficiencies mainly in the visible range. Much less research has been focused on realizing near-infrared narrowband devices. Here, we demonstrate fully vacuum-processed narrow- and broadband photomultiplication-type organic photodetectors. Devices are based on enhanced hole injection leading to a maximum external quantum efficiency of almost 2000% at −10 V for the broadband device. The photomultiplicative effect is also observed in the charge-transfer state absorption region. By making use of an optical cavity device architecture, we enhance the charge-transfer response and demonstrate a wavelength tunable narrowband photomultiplication-type organic photodetector with external quantum efficiencies superior to those of pin-devices. The presented concept can further improve the performance of photodetectors based on the absorption of charge-transfer states, which were so far limited by the low external quantum efficiency provided by these devices.

scholarly journals Pyridinyl-Carbazole Fragments Containing Host Materials for Efficient Green and Blue Phosphorescent OLEDs

Molecules ◽  
2021 ◽  
Vol 26 (15) ◽  
pp. 4615
Author(s):  
Dovydas Blazevicius ◽  
Daiva Tavgeniene ◽  
Simona Sutkuviene ◽  
Ernestas Zaleckas ◽  
Ming-Ruei Jiang ◽  
...  
Keyword(s):  
Current Efficiency ◽  
Quantum Efficiency ◽  
External Quantum Efficiency ◽  
Power Efficiency ◽  
Triplet Energy ◽  
New Host ◽  
High Brightness ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Host Materials

Pyridinyl-carbazole fragments containing low molar mass compounds as host derivatives H1 and H2 were synthesized, investigated, and used for the preparation of electro-phosphorescent organic light-emitting devices (PhOLEDs). The materials demonstrated high stability against thermal decomposition with the decomposition temperatures of 361–386 °C and were suitable for the preparation of thin amorphous and homogeneous layers with very high values of glass transition temperatures of 127–139 °C. It was determined that triplet energy values of the derivatives are, correspondingly, 2.82 eV for the derivative H1 and 2.81 eV for the host H2. The new derivatives were tested as hosts of emitting layers in blue, as well as in green phosphorescent OLEDs. The blue device with 15 wt.% of the iridium(III)[bis(4,6-difluorophenyl)-pyridinato-N,C2′]picolinate (FIrpic) emitter doping ratio in host material H2 exhibited the best overall characteristics with a power efficiency of 24.9 lm/W, a current efficiency of 23.9 cd/A, and high value of 10.3% of external quantum efficiency at 100 cd/m2. The most efficient green PhOLED with 10 wt% of Ir(ppy)3 {tris(2-phenylpyridine)iridium(III)} in the H2 host showed a power efficiency of 34.1 lm/W, current efficiency of 33.9 cd/A, and a high value of 9.4% for external quantum efficiency at a high brightness of 1000 cd/m2, which is required for lighting applications. These characteristics were obtained in non-optimized PhOLEDs under an ordinary laboratory atmosphere and could be improved in the optimization process. The results demonstrate that some of the new host materials are very promising components for the development of efficient phosphorescent devices.

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