Resonant Energy Transfer of CdTe Colloidal Quantum Dots

• Main Authors: Wang, Wei-Jhih, 王威智
• Other Authors: Wu, Ching-Chou
• Format: Others
• Language: en_US
• Published: 2009
• Online Access: http://ndltd.ncl.edu.tw/handle/75124302654663061113

碩士 === 國立交通大學 === 電子物理系所 === 97 === The dynamics of Förster resonance energy transfer (FRET) in mono-dispersed (5.1 nm) and mixed-size (50 % 3.4 nm and 50 % 5.1 nm) water-soluble CdTe quantum dots (QDs) were studied by using photoluminescence (PL) and time-resolved PL (TRPL) spectroscopy. A significant PL energy red-shift was observed for the mono-dispersed CdTe colloidal QDs films when compared with that of the mono-dispersed CdTe colloidal QDs solutions. The energy dependent TRPL spectra directly reveal the energy transfer from small to large QDs. We found that the amount of PL energy red-shift is independent of CdTe QDs’ size but depends on the PL line-width. To study the effect the spectral overlap of donor emission and acceptor absorption on the FRET efficiency, a mixture of two different sizes CdTe QDs (50 % 3.4 nm and 50 % 5.1 nm) was studied. The quenching/enhancement of PL intensity and lifetime of donors/acceptors are evidences of FRET effect in mixed-size water-soluble CdTe QDs. Furthermore, the donor to acceptor concentration ratio in the mixed-size CdTe QDs films is an important parameter to influence the FRET efficiency. As the ratio is increased, the FRET rate and the efficiency is firstly enhanced and then decreased. It is due to the fact that acceptors are surrounded by more and more donors in the beginning. However, the relative amount of available acceptors is decreased if the ratio is further increased.