Transformative Colloidal Nanomaterials for Mid- Infrared Devices.

摘要

The grant focused on the Photoluminescence efficiency of HgTe colloidal quantum dots. The photoluminescence quantum yield of HgTe colloidal quantum dots was measured from 1800 to 6500 cm-1 . There is a steep drop at low energy consistent with the generic gap law. Direct evidence of energy transfer to the CH stretch and overtone vibrations is apparent when temperature tunes the PL wavelength of a given sample through the vibrational resonances. Calculations based on the radiative rate and resonant energy transfer to the ligand vibrations appear to account for much of the quantum yield drop. Power dependent photoluminescence lifetime measurements on 3.7 nm particles show fast , approximately 50 ps, biexciton lifetime similar to other colloidal quantum dot systems of similar sizes. Various synthetic modifications have been explored to increase the PL or the size of the particles, modify the particle composition, with interesting observations but moderate improvements.