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Francisco Fabregat Santiago (B.Sc. in Physics at Universitat de Valencia and University of Leeds in 1995 , Ph.D. from Universitat Jaume I in 2001) joined Universitat Jaume I in 1998 where he is currently full Professor at Physics Department and active member Institute of Advanced Materials (INAM). Among others he made several research stays at Uppsala University, Imperial College, École Polytechnique Fédérale de Lausanne. He authored more than 100 peer reviewed papers and 5 book chapters, that accumulate more than 11000 cites with an h-index of 54. Prof. Fabregat-Santiago is an expert in electro-optical characterization of devices and particularly known by his works in the use of the impedance spectroscopy to model, analyze and interpret the electrical characteristics (charge accumulation, transfer reactions and transport) of films and devices including ZnO and TiO2 nanostructured films (nanocolloids, nanorods and nanotubes), dye sensitized solar cells, perovskite solar cells, electrochromic materials and liquid and solid state hole conductors. His current interests are focused in the in the analysis of the fundamental properties of nano and bio materials for their application in solar cells, water decontamination, bio-energy, sensors and in the (photo)electrochemical production of added value chemicals.
This work studies the photoluminescence of perovskite single crystal made from methylammonium lead bromide (MAPbBr3) with one side partially substituted by iodide (MAPbBrxI3-x). We show that most of the photoinduced charge carriers in MAPbBr3 side may be transferred to the MAPbBrxI3-x region, where they are emitted, meanwhile the MAPbBrxI3-x region is not degraded by moisture. This result implies that photoinduced charge carriers are able to diffuse distances that exceed the 1.5mm length of the single crystal. Very interestingly, exposure to the light excitation yielded to the insertion of bromide ions in the iodide rich side and an increase in the photoluminescence intensity, which we associated to both an improved charge injection and a decrease in non-radiative recombination. The long diffusion length of carriers in single crystal allows the development of high efficiency LEDs, sensors and solar cells. We demonstrate that perovskite the asymetric crystals configuration mimics nature photosystems I and II, and may be used in sensors that collect disperse energy efficiently or to fabricate artificial leaves for electric trees could be produced with such configuration.