Hybrid perovskites have attracted much attention as a promising photovoltaic material in the past few years. Typically, these hybrid perovskites such as methyl ammonium lead halides (MAPbX3) undergo dimensionality reduction from three-dimensional (3D) to zero-dimensional (0D), and finally to PbX2, upon continuous moisture exposure. Our current study shows that 0D-perovskite-related structures exhibit a reversible transformation from a transparent state to a colored 3D state upon exposure to humidity. Fluorescence imaging of individual microcrystals reveals that the structural phase transition could be visualized in the solid state, wherein the crystals transform into cubic crystals. The plausible reason for this transformation is proposed to be a dynamic dissolution and recrystallization of the excess methyl ammonium halide with varying humidity. The thermal and moisture stability are found to be greatly enhanced in the transformed 3D perovskite. Excellent device stability is also demonstrated when the devices are kept under moist (∼70% RH) conditions.

Herein we demonstrate a facile approach for the synthesis of all inorganic cesium lead halide perovskite nanocrystal composites CsPbX3 (X = Cl, Br, I) with high quantum yield by post-synthetic modulation of zero dimensional Cs4PbBr6 nanocrystals with ZnX2 salts.

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Attempts to satisfy the vast demands for electric power in our daily lives and to address the depletion of existing fossil fuels have led to the development of new energy conversion technologies. Herein, we present a different type of electric generation, called ionovoltaic electricity generation (IEG), that results from manipulating organic− inorganic hybrid halide perovskite structures with moisture. This IEG can generate an open-circuit voltage of up to ∼0.5 V and a short-circuit current density of ∼0.1 mA cm −2 , which is sufficient to power small electronic devices. In this work we have utilized the transformation of structurally zero-dimensional perovskite, specifically MA 4 PbBr 6 •2H 2 O, to three-dimensional MAPbBr 3 in the presence of humidity. Flexible power supply devices made of organic−inorganic hybrid perovskite layers are designed and fabricated for harvesting the energy from human breath and some other real-life conditions. This work opens a new direction in the field of organic−inorganic hybrid halide perovskites and offers an extremely simple method for energy conversion of practical importance.

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