NOVELTY - A photovoltaic device comprises a light guiding structure having adjacent inner and outer light guiding regions with a total internal reflection interface between the inner and outer regions. The outer region includes a region of width at least 10 nm containing photoactive material to generate excitations from an evanescent wave arising from total internal reflection of the light at a total internal reflection interface. The photovoltaic device comprises electrical contacts to the photoactive material to provide the electrical energy from the excitations in the photoactive material.    USE - A photovoltaic device, e.g. solar cells.    ADVANTAGE - The photovoltaic device has an enhanced efficiency by using total internal reflections to confine the creation of photonic excitations to a region very close to an interface with a harvesting material.    DETAILED DESCRIPTION - A photovoltaic device comprises a light guiding structure to receive and guide incoming light for conversion to electrical energy by total internal reflection. The structure comprises adjacent inner and outer light guiding regions (1, 2) with a total internal reflection interface between the inner and outer regions. The inner region is exposed to the incoming light and has, at the interface, a refractive index of at least 1.55 for a light wavelength of 1300-300 nm. The outer region has, at the interface, a lower refractive index than the inner region. It includes a region of width at least 10 nm containing photoactive material to generate excitations from an evanescent wave arising from total internal reflection of the light at the interface. The photovoltaic device comprises electrical contacts to the photoactive material to provide the electrical energy from the excitations in the photoactive material. INDEPENDENT CLAIMS are included for:    (1) a method of manufacturing a photovoltaic device; and    (2) a method of converting light energy into electrical energy.    DESCRIPTION OF DRAWING(S) - The drawing is a schematic view of a photovoltaic device.    Inner and outer light guiding regions (1, 2)