Welcome!

The H-Lab is a research group in the School of Engineering and Applied Science at UCLA, led by Professor Yongjie Hu. Motivated by technological challenges, our lab's research focus is on understanding and engineering nanoscale transport phenomena and nanomaterials for wide applications including energy conversion, storage, and thermal management. We use a variety of experimental and theoretical techniques to investigate nanoscale transport processes, with a particular emphasis on design and chemical synthesis of advanced materials, ultrafast optical spectroscopy, pulsed electronics, and thermal spectral mapping techniques. We invite you to look at the website for more details about our work and facilities.



News

Congratulations to H-Lab students: Huan, Huu, Man, and Nicolas for all passing their PhD Candidacy Exam! July 18, 2017

Yongjie has received the Doctoral New Investigator Award from the American Chemical Society (ACS)! Many thanks for the support from ACS PRF!! June 23, 2017

New paper on high-performance flexible thin film thermoelectric devices published in Advanced Materials. March 29, 2017

Congratulations on Joon and Ming's paper published in Nano Letters! This is the first time demonstration of in situ thermal-electrochemical characterization of a 2D van der Waals material based lithium ion battery. Feb 23, 2017

Our team is awarded a competitive research grant as part of UCLA Sustainable LA Grand Challenge! Many thanks to the Sustainable LA Grand Challenge and the Anthony and Jeanne Pritzker Family Foundation!! Dec 21, 2016

Yongjie has received the Air Force Young Investigator Award! Many thanks for the support from AFOSR!! Oct 12, 2016

Welcome new graduate students joining our lab: Nicolas, Man, Julia, Junyu, Huu, Huan! Sept 15, 2016

Electrical-gate tuning of thermoelectric transport in single heterostructure nanowires is published on J. Appl. Phys. . June 15, 2016

We have received a grant support from the US Department of Energy, together with Professors Pilon, Dunn, and Tolbert. We very much appreciate the generous support from DOE! May 20, 2016

Developing a refined technique to measure phonon mean free path distributions is published on Scientific Reports. Nov 27, 2015

Manuscript posted on arXiv: No energy transport without discord: Quantum correlations are mandatory for any energy transport. Oct 16, 2015

Congratulations for the new paper published on Nature Nanotechnology: spectral mapping of thermal conductivity through nanoscale ballistic heat transfer! June 10th, 2015

Congratulations to Joon for passing his PhD Candidacy Exam! May 15, 2015

Developing ultra-high thermal condutivity material - Boron Arsenide, is published on Appl. Phys. Lett.: the first experimental measurement on its thermal conductivity. Feb 20, 2015

Spotlight

imageFirst in situ thermal-electrochemical characterization of 2D van der Waals materials in a lithium ion battery

This work presents the first time demonstration of in situ thermal-electrochemical characterization of a 2D van der Waals material in a lithium ion battery. A novel approach to integrate ultrafast optical spectroscopy and electrochemical control has been developed to investigate the thermal transport in the 2D material electrode (black phosphorus) during the battery's normal operation process. The study reveals intriguing anisotropic ion-phonon interactions and highly reversible electrochemical control over the thermal properties. Feb 23, 2017

imagePaper published in Nature Nanotechnology

This work presents a table-top pump-probe spectroscopy approach to measure phonon spectral contribution to heat transfer. Classical diffusion theory fails to describe small scale energy transport, such as to gauge the temperature rise in modern electronics and thermal solar energy harvesting devices, but the new work provides detailed quatification of such non-equilibrium energy transport down to its spetral contributions. Experimental measurement is compared with modeling resutls based on transient frequency-dependent Boltzmann transport equation and multi-scale Monte Carlo methods, which enables us to better understand heat transfer and design energy materials. June 10, 2015

imageExperimental study of the proposed super-thermal-conductor: BAs in Applied Physics Letters

This work reports the first thermal measurement of Boron Asenide, the new candidate material of ultra-high thermal conductivity for thermal management based on first-principles prediction. Despite high density of vacancy impurities, our measurement shows a reasonable high thermal conductivity, as an important first step towards developing high-conducting materails. Feb 20, 2015