SEM images of three different BNNTs after deposition of C9H16Pt. The rectification measured was 7, 4, and 3%. The arrows denote the direction of heat flow, indicating where the thermal conductance is higher than that of the opposite direction.

APPLICATIONS OF TECHNOLOGY:

• Thermal management for:
• microelectronic devices
• solar cells and solar energy management systems
• refrigerators
• hybrid biological/inorganic systems
• nanoscale calorimeters
• Information transport and processing
• Molecular motors

ADVANTAGES:

• First solid state device to direct heat flow
• Initial tests demonstrate thermal rectification of 7 percent
• Can accommodate high macroscopic thermal current densities

ABSTRACT:

Alex Zettl, Arun Majumdar and colleagues at Berkeley Lab have invented the first solid state thermal rectifier.  The device consists of a boron nitride nanotube (BNNT) loaded at one end with a high mass density material  - specifically, trimethyl cyclopentadienyl platinum (C9H16Pt).  The researchers achieved thermal rectifications as high as 7 percent at room temperature.  Mass loaded carbon nanotubes (CNTs) were found to display thermal rectification of 2 percent.

The Berkeley Lab nanoscale solid state device is to thermal systems what the diode is to electronics.  Controlling the direction of heat flow could lead to radical improvements in thermal management across a range of products.  For example, the Berkeley Lab thermal diode might prevent overheating in microelectronic devices, currently a barrier to significant size reductions.  Since the technology can be designed to handle high macroscopic thermal current densities, it may also lead to more efficient refrigerators, solar cells, and buildings.  The new thermal diode could also result in computing systems that use phonons instead of, or in addition to, electrons for manipulating and transporting information bits.

STATUS:

• Available for licensing.
• Published PCT Patent Application WO2008/042920 available at www.wipo.int.

FOR MORE INFORMATION:

Chang, C.W., Okawa, D., Majumdar, A., Zettl, A.,  “Solid State Thermal Rectifier,” Science 2006, 314, pp. 1121-1124.

REFERENCE NUMBER: IB-2336

SEE THESE OTHER BERKELEY LAB TECHNOLOGIES IN THIS FIELD:

• Thermal Profiling of Nanoscale Circuitry, IB-2363
• Powerful Linear Nanomotor, IB-2011
• Ultra High Performance MEMS/NEMS Actuators, Oscillators, and Sensors, IB-2008
• Air-stable Nanomaterials for Efficient OLEDs and Solar Cells IB-2044, 2231
• Improving the Efficiency of Nanoscale Photovoltaic Devices , IB 2338, 2364, 2365, 2366
• Tunable Thermal Link, IB-2337