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.

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.