Calendar

Feb
7
Thu
Seminar: Ilya Shipster @ Shaffer Hall 2
Feb 7 @ 3:00 pm – 4:00 pm
Feb
14
Thu
Distinguished Lecture Series: Victor Klimov, Los Alamos National Laboratory (The Minkowski Lecture) @ Hodson Hall 210
Feb 14 @ 3:00 pm – 4:00 pm

Abstract: Chemically synthesized quantum dots (QDs) can potentially enable new classes of
highly flexible, spectrally tunable lasers processible from solutions [1,2]. Despite a considerable progress over the past years, colloidal-QD lasing, however, is still at the laboratory stage and an important challenge – realization of lasing with electrical injection – is still unresolved. A major complication, which hinders the progress in this field, is fast nonradiative Auger recombination of gain-active multicarrier species such as trions (charged excitons) and biexcitons [3,4]. Recently, we explored several approaches for mitigating the problem of Auger decay by taking advantage of a new generation of core/multi-shell QDs with a radially graded composition that allow for considerable (nearly complete) suppression of Auger recombination by “softening” the electron and hole confinement potentials [5,6]. Using these specially engineered QDs, we have been able to realize optical gain with direct-current electrical pumping [7], which has been a long-standing goal in the field of colloidal nanostructures. Further, we apply these dots to practically demonstrated the viability of a “zero-threshold-optical-gain” concept using not neutral but negatively charged particles wherein the pre-existing electrons block either partially or completely ground-state absorption [8]. Such charged QDs are optical-gain-ready without excitation and, in principle, can exhibit lasing at vanishingly small pump levels. All of these exciting recent developments demonstrate a considerable promise of colloidal nanomaterials for implementing solution-processible optically and electrically pumped laser devices operating across a wide range of wavelengths.

Feb
21
Thu
Dissertation Defense: Adam Khalifa @ Remsen Hall 101
Feb 21 @ 10:00 am
Mar
15
Fri
Dissertation Defense: Saeed Ashrafinia @ Hurd Hall (Medical Campus)
Mar 15 @ 3:00 pm – 5:00 pm
Apr
11
Thu
Distinguished Lecture Series: Lihong Wang, California Institute of Technology (Kouwenhoven Lecture) @ Hodson Hall 210
Apr 11 @ 3:00 pm – 4:00 pm
Apr
23
Tue
Dissertation Defense: Pegah Ghahremani @ Maryland 110
Apr 23 @ 5:00 pm – 7:00 pm
Apr
24
Wed
Dissertation Defense: Nate Crookston @ Malone 137
Apr 24 @ 12:00 pm – 2:00 pm
May
2
Thu
Seminar: Martin Styner, University of North Carolina @ Shaffer Hall 2
May 2 @ 3:00 pm
May
7
Tue
Dissertation Defense: Kate Fischl @ Shaffer 100
May 7 @ 10:00 am – 12:00 pm
May
21
Tue
Dissertation Defense: Botong Qiu @ Shaffer 101
May 21 @ 10:30 am – 12:30 pm
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