Plasmon-assisted solar cells

Because of its ubiquity in electronics, silicon is the favorite semiconductor used in solar photovoltaic cells. But Si is a poor light emitter and absorber, and the efficiency of thin-film Si PV cells is even poorer than that of wafer-based thick cells. An important goal is to make the cells inexpensive by using thin films, but also to make them nicely absorptive. Scientists at the University of New South Wales in Australia have now enhanced the absorption of sunlight using surface plasmons generated on silver nanoparticles deposited on PV cells. SPs are collective oscillations of conduction electrons that can arise when light impinges on a metal particle whose size is on the order of the light’s wavelength. Strong scattering occurs, and the SPs couple to the waveguide modes of Si; the light is effectively trapped. The researchers used this phenomenon in a PV solar cell to increase the cell’s absorption...