Paper
27 November 2012 The thermal effect of PLEDs by Raman spectra
Zhe Qin, Jian Wang, Ya-jun Chen, Cun-zhou Zhang
Author Affiliations +
Abstract
Raman spectra and infrared imaging systems are used for the study of internal temperatures of PLEDs. The aim is to investigate the thermal degradation of PLEDs with different current densities. Raman intensity is proportional to the number of molecules in the next higher vibration energy level, and accurate internal temperature of PLEDs at thermal equilibrium can be calculated with the ratio of anti-stokes to stokes Raman density by Boltzmann equation. With the current density of PLED going from 0 mA/cm2 to 169 mA/cm2,it is found that the internal temperature of PLED increases accordingly. When the temperature comes to the glass transition temperature (Tg) of the emission layer, there is a phase change in it and the layer becomes free state as liquid, which is not stable. Local disfigurement in the emission layer results in short circuit between the cathode and the anode of a PLED, and the luminescence of PLED fails. Therefore, Raman spectrum is considered as a good method for detecting temperatures of thin-film semiconductor devices.
© (2012) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Zhe Qin, Jian Wang, Ya-jun Chen, and Cun-zhou Zhang "The thermal effect of PLEDs by Raman spectra", Proc. SPIE 8560, LED and Display Technologies II, 85600C (27 November 2012); https://doi.org/10.1117/12.981749
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KEYWORDS
Organic light emitting diodes

Raman spectroscopy

Electroluminescence

Glasses

Infrared radiation

Thermal effects

Thin film devices

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