Degradation of Photoluminescence in CdTe Nanoparticles Due to Cl2 Contamination
Nanostructured CdTe is proving a popular material for a variety of modern applications. Here, we report photoluminescent deterioration of CdTe due to Cl2 contamination. Cl2 gas was bubbled through a 2ml suspension of thioglycolic acid capped CdTe nanoparticles whilst photoluminescence was monitored. With the addition of only 0.02ml of Cl2 a loss of luminescence intensity was observed. Addition of 0.4ml of Cl2 resulted in a 70% loss of luminescence intensity, a 21nm shift in wavelength, and a large narrowing of the full-width-at-half-maximum. Cl2 attacks the Cd-S bond in the thiol capping layer of the nanoparticle, disrupting the passivation of the nanocrystal, and allowing the formation of non-radiative trap states. Smaller nanocrystals with a larger surface area to volume ratio are more heavily affected as is shown in the selective reduction of intensity from the smaller particles resulting in a narrower full-width-at-half-maximum and an apparent photoluminescence shift. A decrease in overall intensity is seen due to the lower number of emitting particles.
S. J. CHUA, J. H. TENG, O. WADA, R. DE LA RUE and X. H. TANG
H. C. Gardner et al., "Degradation of Photoluminescence in CdTe Nanoparticles Due to Cl2 Contamination", Advanced Materials Research, Vol. 31, pp. 150-152, 2008