scholarly journals Influence of the Temperature as an Environmental Factor on the Electrophysical Behavior of Flexible Polymeric Luminescent Devices

2014 ◽  
Vol 2014 ◽  
pp. 1-5
Author(s):  
Mariya Aleksandrova
Keyword(s):  
Indium Tin Oxide ◽  
Measured Temperature ◽  
Temperature Dependent ◽  
Light Emitting ◽  
Ambient Temperatures ◽  
Existing Structures ◽  
Current Voltage ◽  
Operational Temperature ◽  
Polymer Devices ◽  
Dc Current

The effect of operational temperature on the electrophysical properties of polymer based electroluminescent structures is examined. For this purpose thin film of light-emitting semiconductor polyphenylenevinylene derivative is deposited between two indium-tin oxide (ITO) electrodes. DC current-voltage (I-V) characteristics of the fabricated devices ITO/polyphenylenevinylene derivative PPV-D/ITO are measured at varying ambient temperatures, ranging from room temperature (25°C) to 70°C. Several important electrical parameters like a trap factor, traps activation energy distribution, free carriers’ density, trapped carriers density, and effective mobility are estimated from measured temperature dependent I-V curves. Such analysis of the charge transport process in polymer devices may give information needed for optimization of the existing structures.

Transport Properties and Conduction Band Offset of n-ZnO/n-6H-SiC Heterostructures

2006 ◽  
Vol 957 ◽  
Author(s):  
Yahya Alivov ◽  
Xiao Bo ◽  
Fan Qian ◽  
Daniel Johnstone ◽  
Cole Litton ◽  
...  
Keyword(s):  
Conduction Band ◽  
Deep Level Transient Spectroscopy ◽  
Deep Level ◽  
Band Offset ◽  
Measured Temperature ◽  
Temperature Dependent ◽  
Conduction Band Offset ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Transient Spectroscopy

ABSTRACTThe conduction band offset of n-ZnO/n-6H-SiC heterostructures fabricated by rf-sputtered ZnO on commercial n-type 6H-SiC substrates has been measured. Temperature dependent current-voltage characteristics, photocapacitance, and deep level transient spectroscopy measurements showed the conduction band offsets to be 1.25 eV, 1.1 eV, and 1.22 eV, respectively.

Temperature dependent current–voltage curves study of GaN-based blue light-emitting diode

2016 ◽  
Vol 6 (2) ◽  
pp. 205-209 ◽  
Author(s):  
Mingsheng Xu ◽  
Qi Mu ◽  
Longfei Xiao ◽  
Quanbin Zhou ◽  
Hong Wang ◽  
...  
Keyword(s):  
Blue Light ◽  
Light Emitting Diode ◽  
Temperature Dependent ◽  
Light Emitting ◽  
Current Voltage

scholarly journals Investigation of Forward Tunneling Characteristics of InGaN/GaN Blue Light-Emitting Diodes on Freestanding GaN Detached from a Si Substrate

Nanomaterials ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 543 ◽  
Author(s):  
Moonsang Lee ◽  
Hyunkyu Lee ◽  
Keun Song ◽  
Jaekyun Kim
Keyword(s):  
Leakage Current ◽  
Blue Light ◽  
Light Emitting Diodes ◽  
Forward Bias ◽  
Si Substrate ◽  
Temperature Dependent ◽  
Light Emitting ◽  
Current Voltage ◽  
Current Characteristics ◽  
Recombination Current

We report forward tunneling characteristics of InGaN/GaN blue light emitting diodes (LEDs) on freestanding GaN detached from a Si substrate using temperature-dependent current–voltage (T-I-V) measurements. T-I-V analysis revealed that the conduction mechanism of InGaN/GaN LEDs using the homoepitaxial substrate can be distinguished by tunneling, diffusion and recombination current, and series resistance regimes. Their improved crystal quality, inherited from the nature of homoepitaxy, resulted in suppression of forward leakage current. It was also found that the tunneling via heavy holes in InGaN/GaN LEDs using the homoepitaxial substrate can be the main transport mechanism under low forward bias, consequentially leading to the improved forward leakage current characteristics.

Electrical Studies of ZnO Nanowires and Metal Contacts

2015 ◽  
Vol 1131 ◽  
pp. 3-7
Author(s):  
Sattra Thongma ◽  
Artitsupa Boontan ◽  
Thitikorn Boonkoom ◽  
Kittipong Tantisantisom
Keyword(s):  
Indium Tin Oxide ◽  
Optoelectronic Device ◽  
Metal Electrode ◽  
Zno Nanowires ◽  
Metal Contacts ◽  
Voltage Measurement ◽  
Light Emitting ◽  
Current Voltage ◽  
P Type ◽  
A Current

ZnO nanowires are recently used in optoelectronic devices such as sensors, solar cells, and light emitting diodes due to its unique optical and electrical properties. In such devices, a contact between the ZnO nanowires and a metal electrode exists. Hence understanding electrical characteristic between the ZnO nanowires and a metal electrode can facilitate optoelectronic device design. In this work, ZnO nanowires were grown on Indium Tin Oxide (ITO) substrates using a hydrothermal method. Simple devices using the nanowires sandwiched between the ITO and a metal contact (i.e. Au, Al) were fabricated and characterized by a current-voltage measurement. Moreover, studies on p-n junctions between the ZnO nanowires and p-type polymers, poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) and poly(9,9-dioctylfluorene) (PFO), were also fabricated and characterized. The current-voltage measurement of devices clearly shows the rectifying behavior, which is an important characteristic of diodes.

Barrier Properties of Printed Composite Zinc Phthalocyanine/Fullerene Sandwiched between Indium Tin Oxide and Alluminium Electrodes

2013 ◽  
Vol 377 ◽  
pp. 156-160
Author(s):  
Oldrich Zmeskal ◽  
Jan Pospisil ◽  
Jakub Altsmid ◽  
Stanislav Nespurek
Keyword(s):  
Dielectric Spectroscopy ◽  
Indium Tin Oxide ◽  
Barrier Properties ◽  
Charge Carriers ◽  
Zinc Phthalocyanine ◽  
Effective Lifetime ◽  
Current Voltage ◽  
Emission Effect ◽  
Current Voltage Characteristics ◽  
Dc Current

TO/ZnPcSu-PCBM/Al heterostructure was prepared by ink-printing and studied by DC (current-voltage characteristics) and AC (dielectric spectroscopy) techniques (ZnPcSu means 3-diethylamino-1-propylsulphonamide substituted Zn phthalocyanine, PCBM phenyl-C61-butyric acid-methylester fullerene). At the Al contact a Schottky barrier was formed. To explain the shape of current-voltage characteristic two effects had to be taken into account, emission effect, overcoming the potential barrier effect, formed by the superposition of the image Coulombic, space-charge and external potentials, by charge carrier. Dielectric spectroscopy made possible to determine effective lifetime of charge carriers and characteristic time related to electron diffusion; lifetime of charge carriers was τd = 2.10-5 s, and the electron mobility was of order 104 cm2V-1s-1.

Injecting Inter-Layers and the Built-in Potential of Blue Polymer Light-Emitting Diodes

2000 ◽  
Vol 660 ◽  
Author(s):  
Thomas M. Brown ◽  
Ian S. Millard ◽  
David J. Lacey ◽  
Jeremy H. Burroughes ◽  
Richard H. Friend ◽  
...  
Keyword(s):  
Indium Tin Oxide ◽  
Light Emitting Diodes ◽  
Basic Structure ◽  
Thin Layers ◽  
Carrier Injection ◽  
Semiconducting Polymer ◽  
Light Emitting ◽  
Physical Mechanisms ◽  
Organic Solid ◽  
Polymer Light Emitting Diodes

ABSTRACTThe semiconducting-polymer/injecting-electrode heterojunction plays a crucial part in the operation of organic solid state devices. In polymer light-emitting diodes (LEDs), a common fundamental structure employed is Indium-Tin-Oxide/Polymer/Al. However, in order to fabricate efficient devices, alterations to this basic structure have to be carried out. The insertion of thin layers, between the electrodes and the emitting polymer, has been shown to greatly enhance LED performance, although the physical mechanisms underlying this effect remain unclear. Here, we use electro-absorption measurements of the built-in potential to monitor shifts in the barrier height at the electrode/polymer interface. We demonstrate that the main advantage brought about by inter-layers, such as poly(ethylenedioxythiophene)/poly(styrene sulphonic acid) (PEDOT:PSS) at the anode and Ca, LiF and CsF at the cathode, is a marked reduction of the barrier to carrier injection. The electro- absorption results also correlate with the electroluminescent characteristics of the LEDs.

Controlled Injection of Holes into ALQ3 Based Oleds by Means of An Oxidized Transport Layer

2001 ◽  
Vol 708 ◽  
Author(s):  
Mathew K. Mathai ◽  
Keith A. Higginson ◽  
Bing R. Hsieh ◽  
Fotios Papadimitrakopoulos
Keyword(s):  
Indium Tin Oxide ◽  
Oxidative Degradation ◽  
Transport Layer ◽  
Hole Injection ◽  
Carrier Injection ◽  
Salt Loading ◽  
Light Emitting ◽  
Hole Transporting ◽  
Intrinsic Degradation ◽  
Variable Conductivity

ABSTRACTIn this paper we report a method for tuning the extent of hole injection into the active light emitting tris- (8-hydroxyquinoline) aluminum (Alq3) layer in organic light emitting diodes (OLEDs). This is made possible by modifying the indium tin oxide (ITO) anode with an oxidized transport layer (OTL) comprising a hole transporting polycarbonate of N,N'-bis(3-hydroxymethyl)-N,N'-bis(phenyl) benzidine and diethylene glycol (PC-TPB-DEG) doped with varying concentrations of antimonium hexafluoride salt of N,N,N',N'-tetra-p-tolyl-4,4'-biphenyldiamine (TMTPD+ SbF6-). The conductivity of the OTL can be changed over three orders of magnitude depending on salt loading. The analysis of hole and electron current variations in these devices indicates that optimizing the conductivity of the OTL enables the modulation of hole injection into the Alq3 layer. The bipolar charge transport properties for OLEDs in which the interfacial carrier injection barriers have been minimized, are governed by the conductivities of the respective layers and in this case it is shown that the variable conductivity of the OTL does allow for better control of the same. Accordingly, varying the concentration of holes in the device indicates that beyond an optimum concentration of holes, further hole injection results in the formation of light quenching cationic species and the initiation of oxidative degradation processes in the Alq3 layer, thus accelerating the intrinsic degradation of these devices. The variable conductivity of the OTL can hence be used to minimize the occurrence of these processes.

“In-Situ Raman Spectroscopy of Electronic Processes in Fullerene Thin Films

2002 ◽  
Vol 725 ◽  
Author(s):  
S.B. Phelan ◽  
B.S. O'Connell ◽  
G. Farrell ◽  
G. Chambers ◽  
H.J. Byrne
Keyword(s):  
Thin Film ◽  
Indium Tin Oxide ◽  
Low Temperatures ◽  
In Situ Raman Spectroscopy ◽  
State Reduction ◽  
In Situ Raman ◽  
Linear Behavior ◽  
Current Voltage ◽  
Solid State Reduction

AbstractThe current voltage characteristics of C60 thin film sandwich structures fabricated by vacuum deposition on indium tin oxide (ITO) with an aluminium top electrode are presented and discussed. A strongly non-linear behavior and a sharp increase in the device conductivity was observed at relatively low voltages (∼2V), at both room and low temperatures (20K). At room temperature the system is seen to collapse, and in situ Raman measurements indicate a solid state reduction of the fullerene thin film to form a polymeric state. The high conductivity state was seen to be stable at elevated voltages and low temperatures. This state is seen to be reversible with the application of high voltages. At these high voltages the C60 film was seen to sporadically emit white light at randomly localized points analogous to the much documented Electroluminescence in single crystals.

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