A new experimental revelation about black phosphorus nanoribbons should facilitate the future application of this highly promising material to electronic, optoelectronic and thermoelectric devices. A team of Molecular Foundry users working with Jeff Urban in the Inorganic Nanostructures facility has experimentally confirmed strong in-plane anisotropy in thermal conductivity, up to a factor of two, along the zigzag and armchair directions of single-crystal black phosphorous nanoribbons.
The study shows that heat flow in black phosphorous nanoribbons can be very different along different directions in the plane. This thermal conductivity anisotropy has been predicted recently for 2D black phosphorous crystals by theorists but never before observed. Such anisotropy would be a boost for designing energy-efficient transistors and thermoelectric devices, but experimental confirmation proved challenging because of sample preparation and measurement requirements.