Nanoantennas Combined with Semiconductors to Convert Infrared Light into Electricity

A Rice University team analyzing the basic physics of nanomaterials has developed an innovative technology to enhance solar energy panels. Naomi Halas, an engineering professor in Rice, stated that they have attempted to combine the optics of nanoscale antennas with the electronics of semiconductors.

Direct detection of infrared light with silicon is not possible unless a semiconductor is fused to a nanoantenna as discovered by the Rice team. Silicon is normally used to change sunlight into energy in solar panels but they are not capable of trapping infrared light. All semiconductors possess a bandgap where low frequency light travels straight through the material and cannot generate electricity. A metal nanoantenna can be attached to the silicon, such that the nanoantenna is programmed to communicate with infrared light, increasing the frequency range to generate electricity into the infrared. The infrared light strikes the antenna to produce a plasmon, which is an energy wave that passes through the free electrons in the antenna.

The plasmons decompose and discharge energy either by releasing a photon of light or by changing the light into thermal energy. The heating starts as soon as the plasmon transmits its energy to a single electron also termed as a “hot” electron. A metallic nanoantenna was designed on a semiconductor to develop a Schottky barrier to make the infrared light hit the antenna, which would result in the emission of a hot electron that would cross the barrier and produce an electrical current. This is possible for infrared light at frequencies, which if sent through silicon alone would just pass through.