Metal halide perovskites have emerged as versatile photonic device materials because of their outstanding band structure and excellent optical properties. Here, we determined the excitation wavelength dependences of the two-photon absorption coefficient and the Kerr-effect-induced nonlinear refractive index of CH 3 NH 3 PbCl 3 perovskite single crystals by means of the Z-scan method. From theoretical analysis, we found that the electronhole interaction, so-called exciton effect, significantly enhances the nonlinear optical responses even for the interband transitions. This interaction explains the universal relation between the exciton reduced mass and the bandgap for lead halide perovskites.

Surface defects and synthesis methods play important roles in the photoluminescence quantum yield (PLQY), stability, and the device performance of lead halide perovskite quantum dots (PQDs).

Metal halide perovskites have emerged as versatile photonic device materials because of their outstanding optical properties. Here, we report the two-photon absorption (TPA) spectra for CH 3 NH 3 PbBr 3 perovskite single crystals under linearly and circularly polarized laser pulses. We experimentally determined the spin-orbit splitting energy from the TPA linear-circular dichroism spectrum and found the higher-energy band around 0.8 eV above the band edge. From a theoretical analysis of the experimental data, we evaluated the exciton binding energy and the exciton reduced mass. Our findings provide essential information on the electronic structures and carrier dynamics of halide perovskites.