Débute à 
Montréal (Québec) Canada

Low-dimensional metal halide perovskite semiconductors – two-dimensional quantum wells (PQWs) or zero-dimensional quantum dots (PQDs) – are solution-processable and colloidal materials used in optoelectronic devices that rival established commercial technologies, and have recently been found to exhibit coherent single photon emission with long coherence times and fast radiative lifetimes, properties that result from the unique electronic structure of PQDs.

I will first discuss the use of transient absorption and two-dimensional electronic spectroscopy to show that energy transfer between PQWs occurs on timescales of 100s of femtoseconds, and that interwell charge transfer occurs on longer timescales of 100s of picoseconds. By combining observations from photoinduced carrier dynamics with photoelectron spectroscopy experiments that probe energy levels, I am able to reconcile conflicting observations of type-I and type-II band alignment amongst PQWs. This tunable band alignment of PQWs allows them to be employed as interfaces in photovoltaic devices, improving photovoltage and carrier extraction due to favourable band alignment.

Secondly, I will discuss the use of Photon Correlation Fourier Spectroscopy to study PQDs as quantum emitters. This technique allows for the extraction of time-dependent single quantum dot linewidths and coherence times with arbitrary spectral and temporal resolution. Altering the PQD surface ligand dramatically influences photon coherence times and cryogenic lifetimes, highlighting the as-yet untapped potential of these colloidal materials as sources of quantum light – and the need for higher experimental throughput in order to more rapidly screen properties that influence the fidelity of this quantum emission, which I show may be addressed using statistical learning.

 Date et heure: Vendredi 19 mars 2021, 14h00.

 Invitation Zoom: https://umontreal.zoom.us/j/94316213616?pwd=b3ZIMk5SaVQxTVhKTnJZdldlMSs5dz09

ID de réunion : 943 1621 3616

Code secret : un cinq sept zéro un deux


Quantum optoelectronics with low-dimensional colloidal materials - Andrew Proppe (MIT)