Enhanced photoluminescence of water-soluble CdTe nanocrystals induced by light and pyridine

We report an efficient way to improve the photoluminescence (PL) of water-soluble CdTe nanocrystals (NCs) by irradiating the NCs in the presence of pyridine. Under illumination, continuous increases in PL of CdTe NCs were observed. The maximum quantum yield reached up to 41% was obtained, showing five times higher than that of the as prepared parent CdTe NCs. While keeping the illuminated CdTe NCs in dark, further increase in PL quantum yield to over 60% was observed. PL decay measurements revealed that the PL enhancement is associated with the increase of the average lifetime of CdTe NCs. The effects of light wavelength and intensity, pyridine derivatives as well as oxygen on the PL of CdTe NCs were investigated, and a competition mechanism between photodegradation and surface passivation of CdTe NCs induced by illumination and pyridine was suggested.