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

Abstract

Quantum dots (nanoparticles) of cadmium sulphide have been synthesized in N, N′-dimethylformamide (DMF). The preparation shows that particles are air stable for quite some time. Freshly prepared colorless solutions containing CdS 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 CdS 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.