The activity is focussed on the design and the fabrication of an innovative device to directly convert solar energy into electrical power based on optical rectified nano-rectenna.

A rectenna, or rectifying antenna is a device for the conversion of electromagnetic energy propagating through space to direct current in a circuit. It has one or more elements, each consisting of an antenna, filter circuits and a rectifying diode .

In simple microwave antenna theory, the resonant length of the antenna scales linearly with the incident frequency, and in theory the antenna can be scaled to resonate at IR and optical frequencies. However, at IR and optical frequencies, conduction is no longer ohmic, and these simple scaling laws are not accurate. In addition, for solar energy conversion, the antenna must be designed to couple with a fairly complex waveform: the solar radiation is un-polarized and it has a moderately broadband electromagnetic frequency spectrum, ranging from about 150 THz to about 1,000 THz.

Finally, a high frequency diode, such as a Metal-Insulator-Metal tunneling or a most promising geometrical ballistic diode, rectifies the AC field across the antenna, providing DC power to an external load.

The key then is to develop a rectifying diodes that are sufficiently non-linear and asymmetric (in term of I-V characteristic) to have good responsivity with no external bias applied. Additionally a low impedence is required to be matched to the antenna aperture.

M. Lomascolo, A. de Risi, F. Quaranta, I. Farella, A. Cretì 

Activity in collaboration with Dept. of Engineering of Innovation University of Salento (Lecce), and NANOTEC-CNR (Lecce).

Project founded by POR- regione Puglia "Nano-Rectenna for high Efficiency Direct Conversion of Sunlight to Electricity"