Theory of Light-Modulated Emission Spectroscopy.

Perovskite solar cells and fluorescent collectors formed by a dispersion of quantum dots in a transparent solid are paradigmatic devices for photon capture and utilization that involve the coupling of photon displacement, absorption and regeneration. In order to obtain information about the coupled photonic processes in systems involving photon recycling, we analyze the transfer function for modulated outgoing to incoming photon flux. We show the physical features of light-to-light impedance that reveals a trap-limited diffusion of photons coupled with the nonradiative recombination.

Conditions for diffusion-limited and reaction-limited recombination in nanostructured solar cells.

The performance of Dye-sensitized solar cells (DSC) and related devices made of nanostructured semiconductors relies on a good charge separation, which in turn is achieved by favoring charge transport against recombination. Although both processes occur at very different time scales, hence ensuring good charge separation, in certain cases the kinetics of transport and recombination can be connected, either in a direct or an indirect way. In this work, the connection between electron transport and recombination in nanostructured solar cells is studied both theoretically and by Monte Carlo simulation.

Nonuniversality of roughness exponent of quasistatic fracture surfaces.

Numerous experiments have indicated that the fracture front (in three dimensions) and crack lines (in two dimensions) in disordered solids and rocklike materials is rough. It has been argued that the roughness exponent ζ is universal. Using extensive simulations of a two-dimensional model, we provide strong evidence that if extended correlations and anisotropy-two features that are prevalent in many materials-are incorporated in the models that are used in the numerical simulation of crack propagation, then ζ will vary considerably with the extent of the correlations and anisotropy.