2026-09-19T19:58:42Z https://www.ideals.illinois.edu/oai-pmh

oai:www.ideals.illinois.edu:2142/132802 2026-03-24 col_2142_5131 col_2142_14789 com_2142_5130 com_2142_14788 com_2142_8903

application/pdf en text Submission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2027-12-01 The student, Zhengyi Bian, accepted the attached license on 2025-12-05 at 08:20. The student, Zhengyi Bian, submitted this Dissertation for approval on 2025-12-05 at 08:23. This Dissertation was approved for publication on 2025-12-05 at 16:42. DSpace SAF Submission Ingestion Package generated from Vireo submission #23075 on 2026-02-19 at 20:10:03 From purification, spectroscopy, and microscopy of carbon dots to synthesis modeling and AI-assisted spectral data extraction Bian, Zhengyi 2025-12-05 Gruebele, Martin Gruebele, Martin Nie, Shuming Link, Stephan Landes, Christy F. Carbon dots STM Data Collection eng Carbon dots (CDs) occupy a unique niche among nano-sized fluorescent materials. This dissertation integrates purification-first experiments, single-particle multimodal characterization, physical modeling, and AI-assisted data curation. Part A develops and applies rigorous purification and fractionation to disentangle bottom-up products of CD synthesis from confounding small molecules; it then combines ensemble spectroscopy with single-particle fluorescence (Eric Gomez) and scanning tunneling microscopy to quantify intrinsic absorption, bandgaps, blinking behavior, and structure–emission correlations. Building on this foundation, I engineer an impurity-free CD–dye hybrid that converts blue–green emissive CDs to red emission via near-ideal spectral overlap and short donor–acceptor separation, demonstrating a scalable path to color-tunable emitters. To enable electronic and optical probing, I fabricate ultrathin, atomically flat, and semi-transparent template-stripped Au films that simultaneously support scanning tunneling microscopy and single-particle photoluminescence, unlocking direct structure–property mapping at the single-dot level simultaneously. Part B advances a mechanistic view of bottom-up CD synthesis by formulating a Monte-Carlo–based dynamics framework for CD assembly. It then addresses the data bottleneck that limits ML for spectroscopy by creating an LLM-assisted, high-throughput pipeline that collect machine-readable structure–solvent–spectrum data at scale. Overall, the dissertation (i) establishes purification and single-particle standards that separate CD signals from artifacts, (ii) delivers practical routes to color-tunable CD emitters, STM/PL characterization of single CDs, and assembly process modelling, and (iii) bridges experiments and AI by converting the spectroscopy literature into large, usable datasets. These advances provide a reproducible foundation and scalable data infrastructure for CD photophysics and, more broadly, AI materials discovery. 2025-12 Thesis https://hdl.handle.net/2142/132802 Copyright 2025 Zhengyi Bian Chemistry Chemistry University of Illinois Urbana-Champaign Ph.D. Dissertation