Determination of the ensemble transition dipole moments of self-assembled quantum dot films by time and angle resolved emission spectroscopy measurements

The spontaneous emission of light in semiconductors is due to the excitonic relaxation. The emission of light requires a change in the transition dipole matrix, which is captured in the physical quantity called transition dipole moment (TDM). The TDM characterizes the line strength of light emission. TDM's orientation is of importance, as it determines the optical power output of light emitters. Spherical alloyed quantum dots (AQDs) are synthesized in hydrophobic phase and used as isotropic emitters. The AQDs are then self-assembled into layers by the Langmuir-Schaefer method. The ensemble averaged magnitude and orientation of TDM, of layers can be extracted from the time and angle resolved emission spectroscopy (ARES) measurements, respectively. This poster describes the instrumentation details of a home-built ARES system and the system is benchmarked with AQD layers. The measured TDM anisotropy parameter was 0.349, which is within 5% of the ideal value 0.333.