Search results for "Diode"
showing 10 items of 469 documents
Solution processable phosphorescent dendrimers based on cyclic phosphazenes for use in organic light emitting diodes (OLEDs)
2008
A novel solution processable phosphorescent dendrimer based on cyclic phosphazene (CP) cores has been prepared and used as emissive layers in simple OLED architectures, providing efficiencies of 24.0 cd A^-1 and 16.7 lm W^-1. Bolink, Henk, Henk.Bolink@uv.es ; Garcia Santamaria, Sonsoles Amor, Sonsoles.Garcia@uv.es
Sputtered transparent electrodes for optoelectronic devices
2021
Summary Transparent electrodes and metal contacts deposited by magnetron sputtering find applications in numerous state-of-the-art optoelectronic devices, such as solar cells and light-emitting diodes. However, the deposition of such thin films may damage underlying sensitive device layers due to plasma emission and particle impact. Inserting a buffer layer to shield against such damage is a common mitigation approach. We start this review by describing how sputtered transparent top electrodes have become archetypal for a broad range of optoelectronic devices and then discuss the possible detrimental consequences of sputter damage on device performance. Next, we review common buffer-layer m…
High Performance Solar Blind Detectors based on AlGaN grown by MBE and MOCVD
2004
ABSTRACTSolar blind detectors based on AlGaN grown by Molecular Beam Epitaxy and Metal Organic Vapor Phase Epitaxy have been fabricated and characterized. Metal Semiconductor Metal (MSM) detectors and vertical Schottky detectors have been realized, with a design that allows back side illumination. The growth was optimized in order to improve the layer quality, avoid crack formation, and provide the best detector performance. The technological process was also optimized in order to reduce the dark currents and improve the spectral rejection ratio, which is a key factor for solar blind detection. As a result, a rejection ratio of 5 decades between the UV (below 300 nm) and 400 nm, and a steep…
Designing voltage multipliers with nanofluidic diodes immersed in aqueous salt solutions.
2016
[EN] Membranes with nanofluidic diodes allow the selective control of molecules in physiological salt solutions at ambient temperature. The electrical coupling of the membranes with conventional electronic elements such as capacitors suggests opportunities for the external monitoring of sensors and actuators. We demonstrate experimentally and theoretically the voltage multiplier functionality of simple electrical networks composed of membranes with conical nanopores coupled to load capacitors. The robust operation of half and full wave voltage multipliers is achieved in a broad range of experimental conditions (single pore and multipore membranes, electrolyte concentrations, voltage amplitu…
Comparativeab initiostudy of half-Heusler compounds for optoelectronic applications
2010
For the advancement of optoelectronic applications, such as thin-film solar cells or laser diodes, there is a strong demand for new semiconductor materials with tailored structural and electronic properties. The eight-electron half-Heusler compounds include many promising materials with a big variety of lattice constants and band gaps. So far only a small number of them have been investigated. With the help of ab initio calculations, we have studied all possible configurations of ternary 1:1:1 compounds in the half-Heusler structure. We have investigated 648 half-Heusler materials, including compounds of the types I-I-VI, I-II-V, I-III-IV, II-II-IV, and II-III-III. For all compounds, we hav…
Negative capacitance caused by electron injection through interfacial states in organic light-emitting diodes
2006
The negative capacitance frequently observed at low frequencies in organic light-emitting diodes (LEDs) is explained as a signature of sequential electron injection at the organic/metal interface first to states in the bandgap in the dipole layer and then to bulk states. The negative capacitance occurs when the interfacial states depart from equilibrium with the metal Fermi level due to an increasing rate of hopping to the bulk states. A simple kinetic model compares well with the experimental results and provides a new tool to investigate interfacial properties for improving the performance of organic LEDs.
The effect of band gap alignment on the hole transport from semiconducting block copolymers to quantum dots
2013
Semiconducting hole transporting block copolymers were chemically modified to adjust their energy levels to that of CdSe/CdS/CdZnS red quantum dots. Hybrids with optimized energy levels could be used to build strongly improved quantum dot based LEDs (QLEDs).
Tenfold increase in efficiency from a reference blue OLED
2018
Abstract Starting from a reference single-layer light-emitting diode based on the blue phosphorescent bis-cyclometallated iridium complex FIrpic as guest, hosted in a PVK (non-conjugated poly(vynilcarbazole)) matrix, different strategies are followed to improve the efficiency of the devices through the combination of solution processed and evaporated layers. Injection of charges from the electrodes has been varied by using different conductive PEDOT: PSS as hole injection layer and a nanoscale Cs2CO3 interlayer as electron injection and hole-blocking film. Furthermore, a separated electron injection/hole blocking evaporated layer, TPBi or 3TPYMB, is introduced in double-layer devices to enh…
Responsivity measurements of 4H-SiC Schottky photodiodes for UV light monitoring
2014
We report on the design and the electro-optical characterization of a novel class of 4H-SiC vertical Schottky UV detectors, based on the pinch-off surface effect and obtained employing Ni2Si interdigitated strips. We have measured, in dark conditions, the forward and reverse I–V characteristics as a function of the temperature and the C–V characteristics. Responsivity measurements of the devices, as a function of the wavelength (in the 200 – 400 nm range), of the package temperature and of the applied reverse bias are reported. We compared devices featured by different strip pitch size, and found that the 10 μm device pitch exhibits the best results, being the best compromise in terms of fu…
CW and Q-switched diode end-pumped Nd:YAP laser at 1.34 µm. Influence of Nd doping level
2001
A multi watt CW 1.34 µm diode end-pumped Nd:YAP laser is described. Acoustooptic device is tested to obtain Q-switched operation. The influence of the Nd3+ doping level in YAP crystal on the laser efficiency, in CW and in Q-switched mode, is presented.