Search results for "ELECTROLUMINESCENCE"

Photoemission of electrons into electrolyte from cadmium oxide layers formed by anodic oxidation of undeformed and plastically deformed cadmium plates

1995

Studies of electron emission (external photoeffect) at the electrode/solution interface are an important part of contemporary photoelectrochemistry. The results of systematic studies of this phenomenon led to the formulation of fundamental relationships and to new methods for investigation of the physicochemical processes occurring at the electrode-electrolyte interface [1-4]. In particular, photoemission measurements enabled a number of parameters relating to the structure of the semiconductor/electrolyte interface to be determined. The photoemission current from semiconductors with many surface states to solutions with a sufficiently high electrolyte concentration is described by the well…

Tetra-alkoxy substituted PPV derivatives: a new class of highly soluble liquid crystalline conjugated polymers

2011

Two first examples of highly soluble tetra-alkoxy substituted PPV derivatives, poly(2,3,5,6-tetrahexyloxy-1,4-phenylene vinylene) (TH-PPV) and poly[2,3,5,6-tetra(2'-ethyl-hexyloxy)-1,4-phenylene vinylene] TEH-PPV, are presented. Both polymers have been fully characterized and the solubility and UV-Vis absorption characteristics have been studied in various organic solvents. Due to the symmetric nature of the repeating unit, TH-PPV and TEH-PPV have an inherently regioregular nature, which is unusual for PPV-type polymers. Observations from polarized light microscopy and differential scanning calorimetry indicate that TH-PPV exhibits thermally induced order resulting in a liquid crystalline m…

Effect of plastic deformation on the anodic electroluminescence accompanying the early stage of electrolytic oxidation of cadmium

1995

Efficient Polymer Light‐Emitting Diode Using Air‐Stable Metal Oxides as Electrodes

2009

Poly(phenylenevinylene)‐based organic light‐emitting diodes (OLEDs) are fabricated using air‐stable metal oxides as electrodes, producing very efficient and bright electroluminescent devices. Efficiencies of 8 cd A−1 and luminances above 20000 cd m−2 are obtained, comparable to the values reported for classic OLED structures using reactive metals as cathodes.

Near-UV to red-emitting charged bis-cyclometallated iridium(iii) complexes for light-emitting electrochemical cells

2011

Herein we report a series of charged iridium complexes emitting from near-UV to red using carbene-based N^C: ancillary ligands. Synthesis, photophysical and electrochemical properties of this series are described in detail together with X-ray crystal structures. Density Functional Theory calculations show that the emission originates from the cyclometallated main ligand, in contrast to commonly designed charged complexes using bidentate N^N ancillary ligands, where the emission originates from the ancillary N^N ligand. The radiative process of this series of compounds is characterized by relatively low photoluminescence quantum yields in solution that is ascribed to non-radiative deactivati…

Effects of 5 MeV electron irradiation on deep traps and electroluminescence from near-UV InGaN/GaN single quantum well light-emitting diodes with and…

2020

The electrical properties, electroluminescence (EL) power output and deep trap spectra were studied before and after 5 MeV electron irradiation of near-UV single-quantum-well (SQW) light-emitting diodes (LED) structures differing by the presence or absence of InAlN superlattice underlayers (InAlN SL UL). The presence of the underlayer is found to remarkably increase the EL output power and the radiation tolerance of LEDs, which correlates with a much lower and more slowly changing density of deep traps in the QW region with radiation dose, and the higher lifetime of charge carriers, manifested by higher short-circuit current and open-circuit voltage in current–voltage characteristics under …

Electroluminescence of (Pb0.91La0.09)(Zr0.65Ti0.35)O3 relaxor ceramics

2013

Abstract Lanthanum doped lead zirconate titanate (PLZT) relaxor ceramics with (Pb 0.91 La 0.09 )(Zr 0.65 Ti 0.35 )O 3 composition exhibit a repolarization induced by electroluminescence (EL) with a pronounced discrete character of emission. It is established that this behavior is related to the reorientation of nanodimensional polar regions in a strong pulsed electric field in the vicinity of a smeared phase transition. The time and temperature dependences of the EL intensity are studied.

Silicon-based light-emitting devices: Properties and applications of crystalline, amorphous and er-doped nanoclusters

2006

In this paper, we summarize the results of an extensive investigation on the properties of MOS-type light-emitting devices based on silicon nanostructures. The performances of crystalline, amorphous, and Er-doped Si nanostructures are presented and compared. We show that all devices are extremely stable and robust, resulting in an intense room temperature electroluminescence (EL) at around 900 nm or at 1.54 μm. Amorphous nanoclusters are more conductive than the crystalline counterpart. In contrast, nonradiative processes seem to be more efficient for amorphous clusters resulting in a lower quantum efficiency. Erbium doping results in the presence of an intense EL at 1.54 μm with a concomit…

Amplified Spontaneous Emission Properties of Solution Processed CsPbBr3 Perovskite Thin Films

2017

Metal halide perovskites are currently emerging as highly promising optoelectronic materials. It has been recently demonstrated that fully inorganic solution processed CsPbBr3 perovskite thin films show good electroluminescence properties combined with high thermal stability. In this work, we investigate in details the amplified spontaneous emission (ASE) properties of CsPbBr3 perovskite thin films, as a function of the temperature and the trap density, modified by changing the CsBr-PbBr2 precursor concentration. ASE is observed in samples from both CsBr-rich solution (low trap density) and equimolar solution (higher trap density), up to about 150 K, with a minimum threshold of 26 and 29 mu…

Host–guest blue light-emitting electrochemical cells

2014

Carbazole, a commonly used hole-transporter for organic electronics, has been modified with an imidazolium cation and a hexafluorophosphate counter-anion to give an ionic hole-transporter. It has been applied as one of the hosts in a host–guest blue light-emitting electrochemical cell (LEC) with the neutral blue emitter FIrPic. We have obtained efficient and bright blue LECs with an electroluminescence maximum at 474 nm and efficacy of 5 cd A−1 at a luminance of 420 cd m−2, thereby demonstrating the potential of the ionic organic charge-transporters and of the host–guest architecture for LECs.