aspuru-list June 2017

aspuru-list@lists.fas.harvard.edu

15 participants
35 discussions

[Aspuru-Guzik Group List] Goodbye drinks Tuesday night

by Nicolas Sawaya

Hello AAGers! We're planning to have some goodbye/congratulations drinks tomorrow (Tuesday) night for our very own Eric Fried. Eric is a (former) undergrad who worked with us last summer and then remotely from USC. He's going to work at NASA and then at Rigetti. *7pm at John Harvard's*! Cheers, Nicolas

6 years, 11 months

[Aspuru-Guzik Group List] Boston Area Excitonics: June 8th 6pm

by Christoph Kreisbeck

Dear Boston Area Excitonics Community, We are approaching our next Seminar on *Thursday, June 8th*. For this seminar we will have Deniz Bozyigit (ONE Lab, MIT) as our speaker. The title and abstract can be found below. This time we will be at *Harvard, 12 Oxford St. in the Cabot Division Room (M-102)*. Food will be served *at 6 pm* with the talks starting shortly there after. If you plan to attend, please sign-up here so we can have an accurate headcount for food: https://www.surveymonkey.com/r/RBZY6RY Please join us for the Boston Area Excitonics seminar, Doran and Christoph *Deniz Bozyigit* *Understanding charge and energy flow in nanocrystal-semiconductors* The advances in controlling matter on the nanoscale in the last decades have enabled us to use the quantum mechanical effects for new applications and materials. One of the materials that have attracted significant interest are chemically synthesized semiconductor nanocrystals (NCs), which utilize the quantum size effect to tune their optical and electronic properties. Although first NC-based products have become commercially available and promising performances have been reported for NC-LEDs [1] and NC-solar cells [2], the understanding of the fundamental optoelectronic processes remains a challenge that limits the rational improvement of these materials. Here, I will discuss the different physical processes that govern the flow of charge and energy in NC-materials and devices. Quantum confinement and the form of the exciton wavefunction play a particular role. In NC-LEDs, a change in quantum confinement can be used to trade off two effects that limit LED efficiency: Auger-recombination and the Stark-effect of the electric field [3]. In NC-solar cells, changing the quantum confinement and distance between NCs not only modifies the band gap, but also strongly changes the charge carrier mobility [4]. Further, I’ll discuss the role of phonons and their coupling to electrons in the loss of energy in NC-semiconductors. Using a combination of inelastic neutron scattering, ab-initio molecular dynamics and thermal admittance spectroscopy, I’ll show that the soft internal surfaces of the nanostructured solids provide strong coupling of electrons to phonons, which promotes the non-radiative recombination of charge carriers [5] and discuss how these surfaces may be improved. [1] Mashford, B. S. et al., Nat. Photonics *7*, 407 (2013). [2] Chuang, C.-H. M. et al. Nat. Mater. *13*, 796 (2014). [3] Bozyigit, D., et al., Adv. Funct. Mater. *23*, 3024 (2013) [4] Bozyigit, D., et al. Nat. Commun. 6:6180 doi: 10.1038/ncomms7180 (2015) [5] Bozyigit, D., et al. Nature *531*, 618 (2016)

6 years, 11 months

[Aspuru-Guzik Group List] [Reminder] Seminar Kochise Bennett: Friday 4pm-5:30pm

by Siria Serrano

Everyone, A reminder that Kochise Bennett will give a Seminar on Friday at 4pm-5:30 pm in *Mallinckrodt 217* (in the Department Center) and *everyone is encouraged to attend!* Please find below Kochise's title and abstract. Cheers, Siria Title: *Ultrafast X-ray Diffraction in Single-Molecules: Signatures of Electronic Coherence* Abstract: Ultrafast time-resolved X-ray scattering made possible by novel light sources provides a wealth of information about electronic and nuclear molecular dynamical processes. The technique goes beyond merely revealing the time dependent electronic charge density traditionally used in structure determination, also monitoring the interplay of elastic and inelastic processes, nonadiabatic dynamics and electronic coherences. The various ground and excited state contributions to ultrafast diffraction from molecules in crystals, in the gas phase, and from single molecules are surveyed and illustrated by excited state nonadiabatic dynamics simulations of NaF. -- *Siria Serrano* *Faculty Assistant* *Aspuru-Guzik Group* *Harvard University **Department of Chemistry and Chemical Biology* *12 Oxford St. M 136* *Cambridge, MA 02138* *P:** (617) 496-1716 <%28617%29%20496-1716>** F: **617-496-9411 <617-496-9411>*

6 years, 11 months

[Aspuru-Guzik Group List] submitted EFRC podcast

by Marc A Baldo

Hello everyone, I'd like to share the EFRC podcast that we submitted yesterday. Special thanks to Cole Perkinson for producing the podcast, as well as writing, narrating, and generating the image. Also thanks to Mengfei Wu for writing, narrating, editing and generating the image; Nadav Geva for narrating and editing; and Lea Nienhaus for editing. https://dl.dropboxusercontent.com/u/46383360/EFRC_CenterForExcitonics_Upcon… https://dl.dropboxusercontent.com/u/46383360/podcast_graphic.png Good luck in the competition! -marc Professor of Electrical Engineering and Computer Science Director of the Center for Excitonics Director of the Research Laboratory of Electronics

6 years, 11 months

[Aspuru-Guzik Group List] Excitonics Subgroup Meeting Rescheduled to June 19th

by Siria Serrano

Group Members, Tomorrow's Excitonics Subgroup Meeting is now rescheduled to Monday, June 19th, 230-330 PM. Cheers, Siria -- *Siria Serrano* *Faculty Assistant* *Aspuru-Guzik Group* *Harvard University **Department of Chemistry and Chemical Biology* *12 Oxford St. M 136* *Cambridge, MA 02138* *P:** (617) 496-1716 <%28617%29%20496-1716>** F: **617-496-9411 <617-496-9411>*

6 years, 11 months

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aspuru-list June 2017