Photodetectors are designed, which operate in the broadband regime upon bottom illumination (from the indium tin oxide (ITO) side) and in the narrowband regime upon top illumination (from the air/perovskite side). The narrowband photodetectors show high external quantum efficiency of above 10 %. The operational spectrum of the photodetectors can also be tuned by adjusting the halide composition in the active material.

The fields of photovoltaics, photodetection and light emission have seen tremendous activity in recent years with the advent of hybrid organic-inorganic perovskites. Yet, there have been far fewer reports of perovskite-based field-effect transistors. The lateral and interfacial transport requirements of transistors make them particularly vulnerable to surface contamination and defects rife in polycrystalline films and bulk single crystals. Here, we demonstrate a spatially-confined inverse temperature crystallization strategy which synthesizes micrometre-thin single crystals of methylammonium lead halide perovskites MAPbX3 (X = Cl, Br, I) with sub-nanometer surface roughness and very low surface contamination. These benefit the integration of MAPbX3 crystals into ambipolar transistors and yield record, room-temperature field-effect mobility up to 4.7 and 1.5 cm2 V−1 s−1 in p and n channel devices respectively, with 104 to 105 on-off ratio and low turn-on voltages. This work paves the way for integrating hybrid perovskite crystals into printed, flexible and transparent electronics.

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Movie S1: Heating process (AVI) Movie S2: Cooling process (AVI) Experimental methods; XRD patterns of MABr and MAI; bandgap calculation; conversion dynamics (PDF)

In this study, the authors demonstrated that a single dose of 3,4-DAP significantly improved DBN. In view of animal studies reporting that micromolar concentrations of 4-aminopyridine increased the excitability of Purkinje cells, it is suggested that the efficacy of 3,4-DAP may be due to an increase of the physiologic inhibitory influence of the vestibulocerebellum on the vestibular nuclei.