Perovskite photoelectric memristors

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Hybrid organic-inorganic lead halide perovskites (APbX, A: organic or inorganic cation, X: halide anion, such as Br, Cl, I) have attracted tremendous interest in photovoltaics and, recently, also in memristor community due to their mixed electronic and ionic conductivity as well as large absorption coefficient. Lately, research efforts have been concentrated on replacing toxic Pb with other nobler metals. Despite some success demonstrated with respect to increased environmental stability of lead-free perovskites, their photovoltaic efficiencies remain low to render them competitive to their Pb analogues. Nevertheless, those materials are proven to be of much more interest to the memristive community, as their defect-rich chemistry allows for effective memristive switching due to the formation of ion-migration-induced conductive filament formation and rupture. All-inorganic and hybrid organic-inorganic lead-free perovskite films (e.g. double perovskites Cs2AgBiBr6) will be investigated in two-terminal devices, either sandwiched between ITO and Al vertical electrodes, or in nanogap-separated (<10 nm) coplanar electrodes towards development of memristive devices operating as artificial synapses. The precursor materials and the deposition process parameters will be carefully tailored to the desired device properties. The nanoscale films will be characterised with atomic force microscopy and scanning electron microscopy and their DC current-voltage and impedance characteristics will be thoroughly studied to obtain a comprehensive understanding of the operational principle. Their photoelectric operation will be also explored via excitation with short light pulses towards optically controlled memories and development of photonic synapses.