Specific features of photoluminescence of CH$_{3}$NH$_{3}$PBI$_{3}$ perovskites synthesized on nanostructured TiO$_2$ surface

The influence of nanostructured titania surface on the photoluminescence of organometallic perovskite CH$_{3}$NH$_{3}$PBI$_{3}$ films is studied. It is found that the CH$_{3}$NH$_{3}$PBI$_{3}$ luminescence intensity and lifetime decrease on the TiO$_2$ surface, which testifies to charge transfer from perovskite to titania. Charge transfer occurs most efficiently for perovskite films synthesized on the surface of mesoporous TiO$_2$ films. The time dependence of magnetic effect on the luminescence of CH$_{3}$NH$_{3}$PBI$_{3}$ on mesoporous TiO$_2$ films is related to the recombination luminescence caused by forward and backward electron transfer between perovskite and titania.