Correlation of size and photoluminescence of single CdSe/ZnS quantum dots

• Main Author: Qejvanaj, Fatjon
• Format: Others
• Language: English
• Published: KTH, Skolan för informations- och kommunikationsteknik (ICT) 2012
• Online Access: http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-99562

In this thesis the correlation between size and emission wavelength of single CdSe/ZnS quantum dots (QDs) has been studied. Based on the quantum confinement model QDs of different size emit light of different wavelength. In order to characterize individual QDs, experiments were carried out using a high-resolution atomic force microscope (AFM) placed on top of an inverted optical microscope. The quantum dots were exited with a high-power diode laser (405 nm) and the spectral response was recorded with a CCD camera attached to a spectrometer. Samples with two different average-sized QDs exhibiting photoluminescence maximum at 600 and 621 nm were prepared by spin-coating a highly diluted QD/toluene solution on cleaned glass cover slides. The results of this thesis verify the theoretical prediction and show on single particle level that with decreasing QD size the emission energy increases.