Junction Temperature Measurements in Deep-UV Light-Emitting Diodes

2004 ◽  
Vol 831 ◽  
Author(s):  
Y. Xi ◽  
J.-Q. Xi ◽  
Th. Gessmann ◽  
J. M. Shah ◽  
J. K. Kim ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Energy Gap ◽  
Uv Light ◽  
Accurate Method ◽  
High Energy ◽  
Junction Temperature ◽  
Forward Voltage ◽  
Light Emitting ◽  
Thermal Paste ◽  
Carrier Temperature

ABSTRACTThe junction temperature of AlGaN/GaN ultraviolet (UV) Light-Emitting Diodes (LEDs) emitting at 295 nm is measured by using the temperature coefficients of the diode forward voltage and emission peak energy. The high-energy slope of the spectrum is explored to measure the carrier temperature. A linear relation between junction temperature and current is found. Analysis of the experimental methods reveals that the diode-forward voltage is the most accurate method (± 3 °C). A theoretical model for the dependence of the diode junction voltage (Vj) on junction temperature (T) is developed that takes into account the temperature dependence of the energy gap. A thermal resistance of 87.6 K/W is obtained with the AlGaN/GaN LED sample mounted with thermal paste on a heat sink.

Highly Efficient Phosphorescent Green Organic Light-Emitting Diodes with High Energy Gap Host Materials

2010 ◽  
Vol 530 (1) ◽  
pp. 83/[239]-90/[246]
Author(s):  
Hoe Min Kim ◽  
Ji Hyun Seo ◽  
Kum Hee Lee ◽  
Hyun Ju Kang ◽  
Seung Soo Yoon ◽  
...  
Keyword(s):  
Light Emitting Diodes ◽  
Energy Gap ◽  
High Energy ◽  
Organic Light Emitting Diodes ◽  
Light Emitting ◽  
Highly Efficient ◽  
Organic Light ◽  
Host Materials

JUNCTION-TEMPERATURE MEASUREMENTS IN GaN UV LIGHT-EMITTING DIODES USING THE DIODE FORWARD VOLTAGE

2004 ◽  
Vol 14 (03) ◽  
pp. 708-713 ◽  
Author(s):  
Y. XI ◽  
E. F. SCHUBERT
Keyword(s):  
Thermal Conduction ◽  
Uv Light ◽  
Junction Temperature ◽  
Effective Density ◽  
Thermal Resistivity ◽  
Bandgap Energy ◽  
Forward Voltage ◽  
Conduction Model ◽  
Light Emitting ◽  
Uv Leds

A theoretical model for the dependence of the diode forward voltage (V f ) on junction temperature (T) is developed. A new expression for d V f / d T is derived that takes into account all relevant contributions to the temperature dependence of the forward voltage including the intrinsic carrier concentration, the bandgap energy, and the effective density of states. Experimental results on the junction temperature of GaN UV LEDs are presented. Excellent agreement between the theoretical and experimental temperature coefficient of the forward voltage ( d V f / d T) is found. The experimentally found linear dependence of the junction temperature on forward current is explained by a thermal conduction model. A thermal resistivity of 342.2 K/W is found for the UV LED.

Fabrication and Characterization of Organic Light-Emitting Diodes Containing Small Molecules Blends as Emissive Layer

2013 ◽  
Vol 795 ◽  
pp. 106-109 ◽  
Author(s):  
Mohd Arif Mohd Sarjidan ◽  
Siti Hajar Basri ◽  
W.H. Abd Majid
Keyword(s):  
Small Molecules ◽  
Light Emitting Diodes ◽  
Energy Gap ◽  
High Energy ◽  
Organic Light Emitting Diodes ◽  
Optical Energy Gap ◽  
Guest Molecules ◽  
Light Emitting ◽  
Organic Light

Organic light-emitting diodes (OLEDs) were fabricated containing guest molecule of Tris (8-hydroxyquinoline) aluminum (Alq3) blend with host molecules of N,N-diphenyl-N,N-bis (3-methylphenyl)-1,1-biphenyl-4,4-diamine (TPD) and 2-(4-biphenylyl)-5-phenyl-1,3,4-oxadiazole (PBD) small molecules. Optical, photoluminescence (PL) and electroluminescence (EL) properties were investigated with respect to blend systems. The obtained optical energy gap and PL intensity in the blend systems increased due to the transfer of high energy from the host to guest molecules. Luminance and current efficiency were enhanced for blended OLEDs as compared to that of pure Alq3, related to high exiton recombination in guest caused by high injection and accumulation of charge carrier.

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