We report the effects of barrier layer on the electroluminescence properties of the SiN-based multilayer light-emitting devices (LEDs). It is found that the emission efficiency is significantly enhanced by more than one order of magnitude compared to that of LED without barrier layer. Meanwhile, the emission wavelength can also be tuned from 620to510nm by controlling the Si∕N ratio of the barrier layer. The improved performance of LEDs can be attributed to the variation in the band offset between the Si-rich SiN well layer and the N-rich SiN barrier layer.

Water soluble CdTe nanocrystals (NCs) of two different sizes capped by thioglycolic acid were synthesized and were dispersed in pure water. We have observed that the emission color of CdTe NCs has been changed in a single droplet of water during the evaporation of the solvent. This is attributed to Förster resonance energy transfer between CdTe NCs, when their concentration becomes high enough to ensure close proximity. By combining our results of photoluminescence with quantitative analysis we conclude that the coupling between different sized CdTe NCs via long-range dipole-dipole interactions was enhanced in aqueous solution due to Brownian motion.

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