Joshua Choi headshot
JC

Joshua J. Choi

Associate Professor
Unit: School of Engineering and Applied Science
Department: Department of Chemical Engineering
Office location and address
Chemical Engineering Building, Room 218
385 McCormick Rd
Charlottesville, Virginia 22903
Education
B.E. ​Cooper Union, 2006
​Ph.D. Cornell University, 2012
Post-Doc ​Columbia University, 2012 - 2014
Biography

oshua J. Choi received B.E. in Chemical Engineering from Cooper Union and Ph.D. in Applied Physics from Cornell University. He then performed postdoctoral research at the Department of Chemistry, Columbia University. He joined the faculty of the Department of Chemical Engineering, University of Virginia as an assistant professor starting in August, 2014. He is a recipient of a NASA Early Career Faculty Award (2015).

At the nanoscale, quantum mechanical effects and various other mechanisms cause the properties of semiconductors to strongly depend on the size, shape and surface of the material. For example, when the size of a semiconductor crystal becomes smaller than the size of electronic wave function (typically few to tens of nanometers in semiconductors), manipulating the spatial extension of the carrier wave function becomes possible simply by changing the size of the crystal. This 'wave function engineering' gives rise to intriguing cases where, depending on the size of the crystal, semiconductors with the identical composition can have drastically different band gaps, carrier-carrier Coulomb interaction strengths and excited state dynamics. In addition to the size-tunability, properties of semiconductor nanomaterials can be manipulated by forming hetero-nanostructures with other semiconductors, metals and organic molecules as well as tuning their collective interactions within their assemblies. This extremely wide tunability in properties of semiconductor nanomaterials presents many intriguing scientific questions and unique opportunities for transformative advances in technological applications. 

Currently, our research group is focused on studying metal-organic perovskites and colloidal quantum dots - both material systems exhibit intriguing properties tunable by design while looking set to revolutionize the field of solution processed optoelectronic devices. We are developing novel and advanced synthetic methods to achieve robust heterostructure formation, surface structure and impurity doping. We seek to understand and control the structure-property relationships in these materials. To this end, we employ a wide variety of techniques, including synchrotron based X-ray diffraction methods, to study their structure and self-assembly behavior from atomic to macroscopic length scales. We also employ optical spectroscopy and electrical transport measurement techniques to examine properties of the materials as functions of their structure. Newly obtained insights are applied to fabrication and testing of prototype devices to demonstrate improved performance. Particularly, our efforts will be focused on solution processing based device fabrication methods to simultaneously achieve a low-cost and high performance required for wide spread commercial deployment.

Perovskites Doped with Quantum Dots for X-ray Radiography
Source: U.S. Department of Homeland Security
September 01, 2020 – August 31, 2025
Collaborative Research: Nanoscale Charge Transfer in Quantum Dots Connected with Molecular Switches
Source: U.S. National Science Foundation (NSF)
August 01, 2020 – July 31, 2023
AS-PHYS-DOE Role of Organic Cations in Organic-Inorganic Perovskite Solar Cells
Source: U.S. Department Of Energy - Chicago
August 01, 2016 – July 31, 2022
EN-CHE Lightweight and Flexible Metal Halide Perovskite Thin Films for High Temperature Solar Cells
Source: U.S. Nasa - Goddard
October 01, 2015 – September 30, 2018
EN-CHE Solar Aviation with High-Performance, Low-Weight and Flexible Perovskite Solar Cells
Source: Virginia Space Grant Consortium
June 01, 2015 – June 01, 2016
CHE 2202: Thermodynamics
Credits: 3
Includes the formulation and analysis of the first and second laws of thermodynamics; energy conservation; concepts of equilibrium, temperature, energy, and entropy; partial molar properties; pure component and mixture equations of state; processes involving energy transfer as work and heat; reversibility and irreversibility; and closed and open systems and cyclic processes. Prerequisite: APMA 2120
APMA 3100: Probability
Credits: 3
A calculus-based introduction to probability theory and its applications in engineering and applied science. Includes counting techniques, conditional probability, independence, discrete and continuous random variables, probability distribution functions, expected value and variance, joint distributions, covariance, correlation, the Central Limit theorem, the Poisson process, an introduction to statistical inference. Prerequisite: APMA 2120 or equivalent.
PHYS 3995: Research
Credits: 3
A research project on a topic in physics carried out under the supervision of a faculty member culminating in a written report. May be taken more than once. (S-SS) Prerequisite: Instructor permission.
CHE 4995: Chemical Engineering Research
Credits: 1–3
Library and laboratory study of an engineering or manufacturing problem conducted in close consultation with a departmental faculty member, often including the design, construction, and operation of laboratory scale equipment. Requires progress reports and a comprehensive written report. Prerequisite: Instructor permission.
CHE 6615: Advanced Thermodynamics
Credits: 3
Development of the thermodynamic laws and derived relations. Application of relations to properties of pure and multicomponent systems at equilibrium in the gaseous, liquid, and solidphases. Prediction and calculation of phase and reaction equilibria in practical systems. Prerequisite: Undergraduate-level thermodynamics or instructor permission.
CHE 7796: Graduate Seminar
Credits: 1
Weekly meetings of graduate students and faculty for presentations and discussion of research in academic and industrial organizations. May be repeated.
CHE 8998: Master's Research
Credits: 1–12
Formal record of student commitment to master's thesis research under the guidance of a faculty advisor. Registration may be repeated as necessary.
CHE 9999: Dissertation Research
Credits: 1–12
Formal record of student commitment to doctoral research under the guidance of a faculty advisor. Registration may be repeated as necessary.
PHYS 9999: PhD Thesis Non-Topical Research
Credits: 1–12
For doctoral dissertation, taken under the supervision of a dissertation director.

NASA Early Career Faculty Award 2015

VSGC New Investigator Award 2015