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. The spectral shapes allow one to distinguish readily photonic recombination and diffusion kinetic phenomena and consequently to determine the physical parameters that control the system's quantum yield for photoluminescence.