Thomas Kempa

Tailoring Light–Matter Interactions in 2D Semiconductors ConspectusTwo-dimensional (2D) crystals have had a sweeping influence on the condensed matter physics and materials science communities for over two decades. Their thinness and ability to be configure...

We'll have a few announcements this week ... First up, we recently published a summary of our contributions to the tuning of light-matter interactions in 2D semiconductors in Accounts of Chemical Research. @pubs.acs.org

doi.org/10.1021/acs....

It was exciting to share a 4 year long passion project that is now bearing fruit. Thank you Dayne Swearer, Stephan Link, and Wei-Shun Chang and ACS PHYS Division for an exciting symposium and the invitation to talk about exciton confinement using our bespoke vdW heterostructures.

Kempa Group at the #acsfall2025 meeting:

Kathryn Kingsbury talk MON at 5pm in 145B

Paul Hanrahan poster on WED (#4326010)

I'm giving talks today at 11:40a, 3:30p, and 5:20p in INOR, PHYS, and COLL in case you want to see our latest tricks in confining excitons.

The inaugural 2D TMDs conference in 2023 was amazing. 2D TMDs 2025 continues the tradition with excellent talks, stimulating discussions, and scenic venues. Excited for 2026 in Singapore! Mega thank you to Manish Chhowalla and Yan Wang!

It was such a pleasure to visit and give a talk at the @mpifkf.bsky.social ... the "noise-free" Precision Lab (2nd photo) is truly impressive. Thank you to Bettina Lotsch and the @lotschgroup.bsky.social for hosting!

Happy to call Dresden home for two months this summer! Spending time at TU Dresden and MPI Halle courtesy of my wonderful host Xinliang Feng. I also wish to thank the Mercator Foundation for the prestigious support making this international exchange possible. If you're in town, come visit!

What an awesome conference on #2D_materials organized by Eugenio Coronado and Alicia Forment of @ICMol_UV and Ángela Sastre and Fernando Fernández of @UniversidadMH! Thank you for the plenary talk invitation and for hosting us in beautiful Alicante.

Manipulation of Valence Trapping through Local Order of Fe3O Units in an Intrinsically Mixed-Valence Coordination Polymer Mixed-valence coordination polymers (CPs) can exhibit enhanced and tunable conductivity and stimulus-driven phase transitions, making them promising new electronic materials. However, the mechanisms of the electron transfer processes that underlie these properties in the solid state merit further study. Here, we report the synthesis of a new mixed-valence CP, FeIII2FeIIO(OAc)6(bpy)2 (OAc = acetate, bpy = 4,4’-bipyridine), which is obtained from the self-assembly of Fe3O(OAc)6 clusters and bpy linkers. Notably, the CP is charge-neutral in its mixed-valence form, making it one of the few established intrinsically mixed-valence CPs. Detailed characterization of the valence and spin states of the constituent Fe ions in the CP via variable-temperature Mössbauer spectroscopy, single-crystal X-ray diffraction, and magnetic susceptibility measurements reveals the occurrence of thermally activated electron transfer (i.e., valence detrapping) and antiferromagnetic exchange between FeII and FeIII ions. Intriguingly, valence-detrapping phenomena are confined to distinct regions of the CP and proceed to varying degrees of completion depending on the solid-state environment of the participating Fe ions. This study presents a convenient strategy for the direct synthesis of intrinsically mixed-valence coordination polymers and highlights the important role of solid-state structural order in manipulating electron transfer mechanisms in Class II Robin-Day mixed-valence materials.

New paper! We show how subtle variations in solid-state environment (i.e. crystal packing) can dramatically alter the mixed-valence characteristics of Fe3O(OAc)6 clusters in a 1D chain. Congrats Kathryn! @pubs.acs.org

pubs.acs.org/doi/full/10....

I'm excited to announce that as of February 2025 I am serving as an Associate Editor at @Nature_NPJ 2D Materials and Applications!

https://www.nature.com/npj2dmaterials/editor

#2D_materials

I had the distinct pleasure of giving a colloquium at @SeoulNatlUni Dept. of Physics today. Thank you to Hong-Gyu Park for your generous hosting and for arranging a Visiting Professor's office for the day :)

https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.4c02638

New paper in @NanoLetters! This collab with @ShojiHall shows that AgCu nanoalloys, prepared by our metal-halide method, perform admirably as CO2 reduction catalysts w/ mass activities higher than the competition. Congrats @martsliwa and all co-authors!...

I am deeply honored and humbled to be the recipient of the No Bell Award from the @RiceUniversity Center for Quantum Materials (#RCQM) for critical contributions to on-time completion of my talk (bell gong was not necessary).

Excited to celebrate with @Kempa_Group

Excited to give another talk about our new platform for quantum emitters and to learn about new ways of integrating emerging materials and qubit candidates into quantum systems.

@RiceUniversity #Workshop_Functional_Quantum_Defects

My favorite airport terminal

A big thank you to @MannixGroup and @StanfordMSE for hosting my visit! It was exciting to share a teaser of our upcoming results in manipulating excitons via unconventional #2d vdW heterostructures. Another great day full of stimulating discussions!

Johns Hopkins to partner with Morgan State for AI-driven ... A $2.7 million NSF grant will launch a program to train a...

technologies.

https://hub.jhu.edu/2024/09/06/johns-hopkins-morgan-state-ai-driven-microelectronics-training/ via @HubJHU

Excited to be a co-PI on this major @NSF funded National Research Traineeship effort we (@JohnsHopkins & @MorganStateU) just secured! It will support student research and practical training in future #microelectronic and #AI...

A quick day trip to meet friends and collaborators @Columbia and @CUNY

Beauty courtesy of science:

Make sure to check out Kathryn's @kkingsbury15 poster at #ACSFall2024 today (Sunday) at noon! Poster #149.

She's done beautiful work to identify valence trapping mechanisms in trinuclear Fe clusters assembled into coordination polymers.

https://pubs.aip.org/aip/jcp/article-lookup/doi/10.1063/5.0206417

Manipulation of excitons is critical to many areas of science & technology. Interfacing 2D semiconductors with molecules opens new opportunities. For details and a hint of coming attractions :) check our @JChemPhys Perspective! @Reynolds_DG @Kempa_Group...

Excited to celebrate 3+ decades of breakthroughs in nanoscience and consider our next steps as a community at the "Titans of the Tiny" symposium. Thank you @CHADNANO and @IINanoNU for the invitation and congratulations on all the milestones!

Every two years I look forward to meeting with friends old and new at the 2D #GRC. I had the pleasure of sharing some fresh results on unconventional 2D heterostructures and the excitonic tricks we can play with them. More to come soon ... 😉

PHYS 2024 Young Investigator Award Winners! Congratulations to the Winners! We are pleased to announc...

Proud to see my first graduate student @TomojitC earn a well deserved accolade! Congratulations, Tom, on receiving an ACS Young Investigator Award in Physical Chemistry!

https://phys-acs.org/phys-2024-young-investigator-award-winners/

authors!

https://pubs.acs.org/doi/10.1021/acsnanoscienceau.3c00028

New paper from @Kempa_Group in @acs Nanosci. Au! @Reynolds_DG led this work and examined how the edge structure & optical properties of 2D TMDs are *very* sensitive to metal flux. Little details can have outsize effects! Congrats to all...

Thank you to each and every speaker, contributor, and assistant who made the #2D_materials symposium at #ACSFall2023 such a success!

@kinglab_pchem, Archana Raja and I really enjoyed organizing this symposium with the mission to bring more chemists into the 2D materials fold.

On my way through the beautiful British countryside to the @2D_TMDs_2023 conference at Churchill College @Cambridge_Uni ... excited for all things #2D this week!