Organic-inorganic halide CH3NH3PbI3 solar cells have attracted enormous attention in recent years due to their remarkable power conversion efficiency. These materials should exhibit interesting spin-dependent properties as well, owing to the strong spin-orbit coupling and broken inversion symmetry. In this work, we consider the spin-dependent optical response of CH3NH3PbI3. We first use density functional theory to compute the ballistic spin current generated by absorption of unpolarized light. We then consider diffusive transport of photogenerated charge and spin for a thin CH3NH3PbI3 layer with a passivated surface and an Ohmic, non-selective back contact. The spin density and spin currents are evaluated by solving the drift-diffusion nist-equations for a simplified 3-dimensional Rashba model of the electronic structure of the valence and conduction bands. We provide expressions for the photon flux required to induce measurable spin densities, and to generate spin currents sufficient for switching an adjacent thin film ferromagnet.
Physical Review B