Stable light emission from cadmium sulphide quantum dots in N,N′,-dimethylformamide

Quantum dots (nanoparticles) of cadmium sulphide have been synthesized in N,N'-dimethylfonnamide (DMF). The preparation shows that particles are air stable for quite some time. Freshly prepared colorless solutions containing US nanoparticles show blue shifts of > 100 nm in their UV-visible absorption, spectra. Bright yellow light emission from the samples was observed when illuminated with 365-nm ultraviolet light. The photoluminescence (PL) measurements showed that the emission wavelengths are at about 530-545 nm; despite small shifts in absorption spectra over a period of time, the PL wavelengths are unchanged. The absorption spectra indicate the particles to be in the range 3 - 5 nm. It is noted that in some cases, the absorption bands are red shifted in the range of about 10-15 nm over a period 72-96 h. The US nanoparticles in DMF show so small a change in absorption wavelength with respect to time that they can be considered highly stable for useful applications. (C) 2002 Elsevier Science B.V. All rights reserved.