Bachelors thesis

Temperature dependence of exciton lifetime in anisotropic CdTe/CdSe heteronanocrystals

Bachelors thesis at the Van't Hoff Laboratory for Physical and Colloid Chemistry, Utrecht University. Supervisor: prof. dr. Andries Meijerink & Esther Groeneveld, MSc.

In literature, the temperature dependence of the exciton lifetime has been shown to strongly decrease between 1.5 and 20 K for various quantum dots (QDs). This was explained by coupling to acoustic phonons in these systems.

In this thesis, the temperature dependence of the exciton lifetime for a different type of QDs is reported: CdSe/CdTe hetero nanostructures. The structures have a size in the order of 2–10 nm and the wavelengths of the emission maxima range from 790–950 nm. A strong decrease of the exciton lifetime is observed in the 1.5–20 K temperature regime. The difference in energy between the first two excited exciton energy states of the investigated hetero nanocrystals are in the order of 0.5–0.9 meV. This is consistent with acoustic phonon energies and suggests a role of acoustic phonons in promoting exciton transition in CdSe/CdTe (core-shell) hetero nanocrystals.