We report a quantitative model of a near-field thermophotovoltaic (TPV) device consisting in a thermal source located in the near field of a TPV cell. The enhanced radiative transfer at short distance leads to an increase of the photogeneration current. We analyze quantitatively other potential near-field effects, in particular, on the dark current. We also study the influence of the modification of the spectrum of the sources in the near field, comparing the case of a tungsten source with the case of a quasimonochromatic source. Our model leads to a quantitative evaluation of the near-field TPV device output electric power and efficiency.

Light forces on small (Rayleigh) particles are usually described as the sum of two terms: the dipolar or gradient force and the scattering or radiation pressure force. The scattering force is traditionally considered proportional to the Poynting vector, which gives the direction and magnitude of the momentum flow. However, as we will show, there is an additional nonconservative contribution to the scattering force arising in a light field with nonuniform helicity. This force is shown to be proportional to the curl of the spin angular momentum of the light field. The relevance of the spin force is illustrated in the simple case of a 2D field geometry arising in the intersection region of two standing waves.