Stability study of organometal halide perovskite and its enhanced X-ray scintillation from the incorporation of anodic TiO2 nanotubes

Abstract

Organometal halide perovskite-based optoelectronic devices are currently a hot research area owing to their unique properties, but widespread commercialization is plagued by their poor long-term stability. So far, the degradation mechanism of organometal halide perovskites is still indistinct due to limited real time systematic study. In this work, we in situ study the crystal evolution of an organometal halide perovskite CH₃NH₃PbI₃, which is prepared on different kinds of framework substrates. Based on the in situ grazing incidence X-ray diffraction and X-ray near absorption edge spectrum, we observe the formation of some 2D networks of [PbI₆]⁴⁻ octahedra intermediates during CH₃NH₃PbI₃ degradation in a moist environment at the early step of the degradation mechanism. We also show that the structural stability of CH₃NH₃PbI₃ deposited anodic TiO₂ nanotube substrates is relatively better than that of prepared perovskite on TiO₂ nanoparticles in moisture. The confinement of the 3D [PbI₆]⁴⁻ octahedral crystal network probability reduces the ion migration by regular pores of crystalline TiO₂ nanotubes, improving the stability of the organometal halide perovskite. Furthermore, the X-ray excited luminescence intensity of CH₃NH₃PbI₃ fabricated on TiO₂ nanotubes is boosted 88% compared with that of conventional TiO₂ nanoparticle substrates, which demonstrates its potential application in scintillation detectors.