Light emitting diode efficiency

Before discussing DLTS, it is appropriate to talk about some device parameters that are affected by these impurities. The main parameters are the recombination and generation lifetimes because they affect junction leakage current, device switching speed, light emitting diode efficiency and a number of other device performance indicators. 

A light-emitting diode (LED) is a forward-biasedp—n junction in which the appHed bias enables the recombination of electrons and holes at the junction, resulting in the emission of photons. This type of light emission resulting from the injection of charged carriers is referred to as electroluminescence. A direct band gap semiconductor is optimal for efficient light emission and thus the majority of the compound semiconductors are potential candidates for efficient LEDs. 

From the perspective of the strategies aimed at fabrication of efficient blue LEDs, the results outlined above regarding yellow LPPP light emitting diodes are, nevertheless, unsatisfactory. In order to prepare blue LEDs from LPPP materials, it is necessary to efficiently mask out or suppress the dominant yellow aggregate emission. 

Schlamp,M.C., Peng, X.G. andAlivisatos, A. P. (1997) Improved efficiencies in light emitting diodes made with CdSe(CdS) core/shell type nanocrystals and a semiconducting polymer./. Appl. Phys., 82, 5837-5842. 

Qian, F. Gradecak, S. Li, Y. Wen, C.-Y. Lieber, C. M. 2005. Core/multishell nanowire heterostructures as multicolor, high-efficiency light-emitting diodes. Nano Lett. 5 2287-2291. 

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