Research Highlights in NEWS

Semimetals as potential thermoelectric materials

  Top 19 most read article in physics in Nature Scientific Report in       2018

Focus: Two Types of Cooling Require Different Designs

  Keeping food cold is thermodynamically different from cooling a hot circuit element—a distinction that is accounted for in the design of a new thermoelectric cooler.
Multifunctional Materials Integration: Cooler Chips Mean Smaller Devices

This article tells the story of the small coolers and why we need them. It highlights how our research group approches the problem. 

How Graphene Could Cool Smartphone, Computer and Other Electronics Chips 2017

Graphene has the record high thermal conductivity. In our recent work we have shown that it also has the record high thermoelectric power factor. While large thermal conductivity enables passive cooling, large thermoelectric power factor enables active cooling. The combination of passive and active cooling enables graphene to be an effective cooler for nanoscale applications.

First principles calculations of solid-state thermionic transport in layered van der Waals heterostructures


A graphene/phosphorene/graphene heterostructure in contact with gold electrodes is studied by using density functional theory (DFT)-based first principles calculations combined with real space Green's function (GF) formalism. We show that for a monolayer phosphorene, quantum tunneling dominates the transport. By adding more phosphorene layers, one can switch from tunneling-dominated transport to thermionic-dominated transport, resulting in transporting more heat per charge carrier, thus, enhancing the cooling coefficient of performance. The use of layered van der Waals heterostructures has two advantages: (a) thermionic transport barriers can be tuned by changing the number of layers, and (b) thermal conductance across these non-covalent structures is very weak.  The thermionic coefficient of performance for the proposed device is 18.5 at 600 K corresponding to an equivalent ZT of 0.13, which is significant for nanoscale devices.

Invisible Dopants   2013

Dopants, which are invisible to the conduction carriers could be designed to increase the carrier mobility. We have shown incorporation of such dopants can potentially  increase the thermoelectric power factor by two orders of magnitude.

‘Invisible’ particles could enhance thermoelectric devices, MIT NEWS

Electronic Cloaking 2012

We have recently found the proper conditions under which invisible nanoparticles are possible to make. The nanoparticles are invisible to the conduction electrons in the sense that the scattering cross section of the electrons off of nanoparticles are 10000 times smaller than the geometrical limit

Nanoparticles in hiding PRL synopsis

"Invisibility" could be a key to better electronics, MIT NEWS

Nature nanotechnology: Nanoparticles, Now you don't

3D modulation-doping 2012

Modulation doping strategy applied to three dimensional nanostructured samples was developed to enhance the carrier mobility and the thermoelectric power factor. Below are some of the links to the media NEWS on this work. For more details, you can read our published articles in Nanoletters.

This work has also mentioned in Kavli Prize manuscript by Prof. M.S. Dresselhaus
Energy  Science Nanotechnology
& Imagination Lab