About Me
- Born and raised in Hubei, China.
- Have been to/lived in a few places around the world.
- Always excited about high tech.
- Newbie skiier
- I will update my GitHub repo one day!
Research Projects
Exciton Delocalization and Chain Conformation in Electron Push-Pull Polymers
Electron push-pull polymers have attracted a significant amount of attention due to their order of magnitude-higher field-effect charge mobility compared to their homoconjugated counterparts. Unlike the traditional conjugated homopolymers, polymers of this kind are composed of monomeric units of electron-sufficient and -deficient domains. The strong charge-transfer character mixes with localized Frenkel-like excitons, which leads to multiple exciton bands throughout the near IR-visible wavelengths. Here, I selected an uprising D-A polymer template, DPP-DTT and the thin films are deposited from solutions of a concentration gradient, thus the excitonic interchain interaction could be tuned:
- Conducted UV absorption and steady-state PL measurements for lineshape analysis and their indications on exciton coupling and delocalization.
- Conducted transient absorption (TA) measurements to probe the excited-state landscapes of electron push-pull polymers.
- Scripted Python codes to analyze and visualize 2D data matrices as well as spectral and temporal distributions.
- Collaborated with Dr. Connor Callaway and Dr. Chad Risko for DFT calculations to assign the Raman modes observed from the experimental Raman spectra.
Exciton-Exciton Annihilation in Electron Push-Pull Conjugated Polymers
EEA has known to dominate the early life-time (~10-100 ps) dynamics. Two possible mechanisms are widely applied and discussed: previously, two mechanisms have been proposed to explain the annihilation process: one is that the annihilation is achieved through F$"o$rster-type long-range Coulombic interaction. Due to the random spatial distribution of excitons, the ensemble-averaged annihilation rates will decrease with time. Another type considers the anisotropy of exciton diffusion, and excitons can only interact when they are in proximity, either through short-range Coulombic interaction or wavefunction overlap. In either scenario, the temporal dependence of the annihilation rates reflects on the spatial dependence of the exciton distribution or their motion. Therefore, the quantification of the annihilation model can reveal key diffusion parameters. This work focuses on understanding the exciton dynamics and exciton exciton annihilation (EEA) in DPP-DTT thin films and acquiring the key diffusion paramters by comparing two time-dependent techniques, TA and excitation-correlation photoluminescence (ECPL) spectroscopy.
- Derived the EEA model for the ECPL detection scheme and simulated the experimental data with the derived formula.
- Simulated the TA data by considering both isotropic and anisotropic exciton diffusion to acquire the diffusion length and coefficients.
Excitonic Coulombic Interactions, Multimode Exciton-Phonon Coupling, Biexciton and Many-body Interactions Revealed by the Two-Dimensional Coherent Spectroscopy.
Yet more to come
This project is a collaboration work with Rahul Venkatesh, a third-year Ph.D. student from Dr. Elsa Reichmanis’s group By utilizing a classification algorithm to screen a data set, composed of processing conditions and electronic properties from 115 organic field-effect transistors from 15 publications, an ideal polymer concentration regime (~5 g/L) has been recognized from the algorithm. Interestingly, 5 g/L is also found to be the critical chain overlap point of the conjugatd polymers in chlorobenzene. Then, thin film transistors are fabricated with different concentrations for experimental testing. The experimental results conformed to the theoretical prediction.
- Conducted viscosity measurements on the conjugated polymer solutions, discovering dilute and semidilute regimes.
- Performed optoelectronic characterizations of thin-film samples, including UV-Vis absorption and OFET measurements.
- Aided a construction of a dataset comprising of processing and performance metrics through broad literature searching.
- Interacted with cross-functional groups for the accomplishment of a final paper publication.
Experiences
- Hands-on experiences on linear and nonlinear high harmonic generation with amplified laser systems, OPA and NOPA, to create high-power and broad-bandwidth pulses.
- Extensive working experiences with free-space nonlinear, ultrafast spectroscopy systems, such as transient absorption (TA), time-correlated single photon counting (TCSPC), fluorescence upconversion, photoluminescence (PL)-detected two-dimensional electronic spectroscopy.
- Hands-on experiences on optical metrology measurements such as absorption and PL spectroscopy, atomic force microscopy (AFM), dynamic and static light scattering (DLS/SLS), cross-polarized optical microscopy (CPOM).
- Experiences in building simulation models in calculating optical features of organic semiconductor polymers as well as data analysis and visualization using Python.
Reichmanis Lab
Graduate Research Assistant
April 2019 - present
https://wordpress.lehigh.edu/reichmanisgroup/
Dr. Reichmanis moved to Lehigh University Nov. 2019, however the supervision and collaboration is still on-going.
- Hands-on experience with spin coating and wire-bar coating.
- Experiences in working in clean room for organic field-effect transistor fabrications.
- Experiences in viscosity measurements for polymer solutions.
Duhamel Lab
Undergraduate Research Assistant
May 2017 - January 2018
https://uwaterloo.ca/chemistry/people-profiles/jean-duhamel
- Hands on experiences with organic synthesis, and purification methods such as dialysis, precipitation and freeze-dry.
- Applied UV, steady-state and time-resolved PL to characterize the content of the dyes and the ratio of excimer to monomer contributions to the total fluorescence spectra.
- Adopted home-written Fluorescence Blob Model (FBM) to simulate and analyze the kinetics of the polymer chain movement.
Education
Georgia Institute of Technology
August 2018 - present
Ph.D Candidate in physical chemistry, specialized in nonlinear, ultrafast spectroscopy, and solid-state physics.
University of Waterloo
July 2016 - April 2018
Bachelor of Science in Chemistry
Huazhong University of Science and Technology
September 2014 - June 2016
Bachelor of Science in Chemistry
Skills
- Coding languages: Python, Matlab
- Softwares: LabVIEW, Mathematica, LaTeX, Sentaurus Lithography, Microsoft office, autoCAD (entry level)
- Languages: Chinese (Native), English (Proficient)
Publication
- please see my Google Scholar profile (https://scholar.google.com/citations?user=pcLymh4AAAAJ&hl=en)