article published yes Seungho Lee author BB243B88-D767-11E9-B658-BC13E66974250000-0002-6962-8598 Daniel Balazs author 302BADF6-85FC-11EA-9E3B-B9493DDC885E0000-0001-7597-043X Aiswarya Rayaroth Puthiyaveettil author 8aceb01b-8972-11ed-ae7b-d5fe53775add Sharona Horta author 03a7e858-01b1-11ec-8b71-99ae6c4a05bc Carl Peter Goodrich author EB352CD2-F68A-11E9-89C5-A432E66974250000-0002-1307-5074 Michael Engel author Ihor Cherniukh author d03b62b2-5976-11ef-a8d7-9525504b7895 Maria Ibáñez author 43C61214-F248-11E8-B48F-1D18A9856A870000-0001-5013-2843 MaIb department LifeSc department GradSch department CaGo department HighTE: The Werner Siemens Laboratory for the High Throughput Discovery of Semiconductors for Waste Heat Recovery project Nanocrystal superlattices are commonly formed by changing concentration, solvent conditions, or particle surface chemistry. Although effective, these approaches alter multiple contributions to the interparticle potential simultaneously, making it difficult to isolate the interactions responsible for ordering or to control assembly in chemically complex environments. Here, we show that oligomeric species present in a nanocrystal reaction medium drive superlattice formation through a depletion mechanism. Using PbTe nanocrystals as a model system, we identify Pb–oleate oligomers in the crude reaction mixture, characterize their solution structure, and quantify their contribution to the interparticle potential, establishing depletion as the dominant short-range interaction governing spontaneous body-centered cubic superlattice formation. We then confirm the depletion origin of ordering by showing that varying depletant concentration predictably shifts the order–disorder boundary and produces a thermally reversible transition between dispersed and ordered states ─ behavior that is inconsistent with van der Waals or ligand-mediated mechanisms but is a direct consequence of depletion control. Having established and validated the mechanism, we demonstrate that the same depletion framework can be deliberately activated in purified dispersions and transferred across nanocrystal systems of different composition and shape, including anisotropic and binary assemblies. These results establish precursor-derived depletion as a general and chemically grounded mechanism for nanocrystal superlattice formation, and show that collective ordering can be programmed through the surrounding medium rather than through particle surface modification. https://research-explorer.ista.ac.at/download/22645/22646/2026_JACS_Lee.pdf application/pdfno American Chemical Society2026 eng 0002-7863 1520-5126 4253290410.1021/jacs.6c07859 1482931245-31252 S. Lee, D. Balazs, A. Rayaroth Puthiyaveettil, S. Horta, C.P. Goodrich, M. Engel, I. Cherniukh, M. Ibáñez, Journal of the AmericanChemical Society 148 (2026) 31245–31252. Lee, Seungho, Daniel Balazs, Aiswarya Rayaroth Puthiyaveettil, Sharona Horta, Carl Peter Goodrich, Michael Engel, Ihor Cherniukh, and Maria Ibáñez. “Reaction Medium Asan Architect of Nanocrystal Superlattices.” <i>Journal of the AmericanChemical Society</i>. American Chemical Society, 2026. <a href="https://doi.org/10.1021/jacs.6c07859">https://doi.org/10.1021/jacs.6c07859</a>. Lee S, Balazs D, Rayaroth Puthiyaveettil A, et al. Reaction medium asan architect of nanocrystal superlattices. <i>Journal of the AmericanChemical Society</i>. 2026;148(29):31245-31252. doi:<a href="https://doi.org/10.1021/jacs.6c07859">10.1021/jacs.6c07859</a> Lee, S., Balazs, D., Rayaroth Puthiyaveettil, A., Horta, S., Goodrich, C. P., Engel, M., … Ibáñez, M. (2026). Reaction medium asan architect of nanocrystal superlattices. <i>Journal of the AmericanChemical Society</i>. American Chemical Society. <a href="https://doi.org/10.1021/jacs.6c07859">https://doi.org/10.1021/jacs.6c07859</a> Lee, Seungho, et al. “Reaction Medium Asan Architect of Nanocrystal Superlattices.” <i>Journal of the AmericanChemical Society</i>, vol. 148, no. 29, American Chemical Society, 2026, pp. 31245–52, doi:<a href="https://doi.org/10.1021/jacs.6c07859">10.1021/jacs.6c07859</a>. S. Lee <i>et al.</i>, “Reaction medium asan architect of nanocrystal superlattices,” <i>Journal of the AmericanChemical Society</i>, vol. 148, no. 29. American Chemical Society, pp. 31245–31252, 2026. Lee S, Balazs D, Rayaroth Puthiyaveettil A, Horta S, Goodrich CP, Engel M, Cherniukh I, Ibáñez M. 2026. Reaction medium asan architect of nanocrystal superlattices. Journal of the AmericanChemical Society. 148(29), 31245–31252. 226452026-08-04T06:29:31Z2026-08-04T06:47:13Z