It is widely accepted that a long photoluminescence (PL) lifetime in metal halide perovskite films is a crucial and favorable factor, as it ensures a large charge diffusion length leading to a high power conversion efficiency (PCE) in solar cells. It has been recently found that vacuumevaporated CH3NH3PbI3 (eMAPI) films show very short PL lifetimes of several nanoseconds. The corresponding solar cells, however, have high photovoltage (>1.1 V) and PCEs (up to 20%). We rationalize this apparent contradiction and show that eMAPI films are characterized by a very high diffusion coefficient D, estimated from modeling the PL kinetics to exceed 1 cm2/s. Such high D values are favorable for long diffusion length as well as fast transport of carriers to film surfaces, where they recombine nonradiatively with surface recombination velocity S ∼ 104 cm/s. Possible physical origins leading to the high D values are also discussed

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Wafers of silicon and compound semiconductors are nanostructured by using electrochemical or chemical etching (stain etching) in etching cell with electrolyte kept by capillary forces. Atomic force microscopy, infrared spectroscopy and Raman scattering methods reveale nanoporous and nanocrystalline structure of the treated surfaces. The formed porous semiconductors demonstrate efficient photoluminescence, which is controlled by etching parameters, i.e. current density, electrolyte content, etc. These results indicate good prospects of the employed capillary-cell method for preparing nanostructured porous materials with desired structure and optical properties.