The Wong Lab

A huge congratulations to Michael and James on their paper, “Ligand-engineered bandgap stability in mixed-halide perovskite LEDs”, which was published today in Nature. A mixture of halides can be used in perovskite NCs to tune their emission wavelength, but upon exposure to light or electrical bias these halides tend to segregate, changing their emission wavelength. Our collaborators at Oxford developed a method using short-chain, multi-dentate ligands to stabilize the surface of perovskite NCs, and we, along with collaborators in Korea, demonstrated that the use of these ligands inhibits halide-segregation. Michael performed incredibly difficult transient absorption measurements on the nanocrystals, trapping them in their segregated state to measure their excited state dynamics and demonstrate the inhibition of segregation upon exposure to light. James and Michael also used dilution studies to show that the mechanism of halide segregation is likely within single nanocrystals. James patiently and carefully wrote and revised large portions of this paper and I hope he and Michael enjoy seeing the culmination of their years of hard work in print at last! Many thanks to all of our collaborators, particularly Yasser Hassan and Henry Snaith for inviting us to be a part of this fruitful collaboration.

In Kelly and Zach’s invited paper in Spectrochim Acta A, we review the different methodologies used to implement single-shot transient absorption spectroscopy, and review design principles for these instruments. It was fun to write this final paper with Kelly as he left for his next position. Great job, all!

Thanks to Prof. Tiglet Besera for the invitation to virtually visit Missouri State University’s Physics Department for a seminar. It was great to have a chance to share our work with their faculty and students.

Zach did a masterful job of presenting his research during his qualifying exam, passing with flying colors. All the studying paid off! Great job, Zach, and to the entire group for helping him prepare – go team!

Thank you to Prof. Jeongho Kim for the invitation to present our work at their 1st International Symposium on Smart Materials and Process towards Sustainable Future. The Department of Chemistry and Chemical Engineering at Inha University was a great place to remotely visit. Thank you for the chance to share our work with all of your students!

A big welcome to our two new rotation students this quarter, Nick D’Antona and Kayd Meldrum. Nick will be working on measuring perovskite nanocrystals during their synthesis, while Kayd will focus on understanding how annealing affects organic films of electron donors and acceptors. We are excited to have them in our lab!

Thanks to Suggy Jang and Chris Bardeen for inviting me to contribute to the fantastic workshop they hosted on the manipulation and application of excitons through the Institute of Theoretical Sciences at CUNY. It has been a great series of workshops and it was an honour to be able to contribute. I presented James’ pioneering work where he utilizes the behavior of excitons to learn about the surface of nanocrystals during their growth. We managed to include some fresh new data as a result of James’ heroic experimental efforts over the past few weeks with the help of Zach, Fischer, and Brandon. Great job, team! A recording of the seminar is available here.

Thanks to Chris Bardeen for inviting me to give a seminar at UC Riverside. Really interesting conversations – some fabulous science being done at Riverside!

A huge congrats to Morgan on her newly published manuscript in J. Chem. Phys.! This paper explains how to model the absorbance spectra of organic molecular aggregates that are a mixture of H- and J-aggregates, and shows the clever method she came up with to fit her simulated spectra to those measured experimentally. This allows her to use simple benchtop in situ absorbance measurements to tell her something about the evolving structure and composition during the aggregation of of organic molecules into thin films. Thanks to Morgan our lab has gone from having no idea how to simulate absorbance spectra to being able to do it for complex aggregate mixtures. Great job, Morgan!!

Kelly’s experiments and Morgan’s simulations were both highlighted at the remote MRS conference this week. Thanks to Brian Collins, Aram Amassian, Eva Hertzig, and Xiaodan Gu who organized the “New Materials Design for Organic Semiconductors Through Multimodel Characterization and Computational Techniques” symposium and for the invitation to give a live keynote presentation. It was a fun symposium with an exciting series of talks!