Coexistence of negative differential resistance (NDR) and resistive switching (RS) memory is observed using a Ag|TiOx|F‐doped‐SnO2 memory cell at room temperature. Unlike other reports, the coexistence of NDR and RS strongly depends on the relative humidity levels at room temperature. The NDR disappears when the cells are placed in a dry air ambient (H2O < 5 ppm) or in vacuum, but the coexistence emerges and gradually becomes obvious after the cells are exposed to ambient air with relative humidity of 35%, and then becomes dramatically enhanced as the relative humidity becomes higher. Due to the excellent stability and reversibility of the coexistence of NDR and RS, a multilevel RS memory is developed at room temperature. Hydroxide ion (OH−) is induced by gas‐phase water‐molecule splitting on the surface and interface of the memory cell. The OH− interacts with oxygen vacancies and transports in the bulk of memory cell to facilitate the migration of Ag ions and oxygen vacancies along grain boundaries. These processes are responsible for the moisture‐modulated and room‐temperature coexistence. This work demonstrates moisture‐modulated coexistence of NDR and RS for the first time and gives an insight into the influence of water molecules on transition‐metal‐oxide‐based RS memory systems.

We study a class of linear network coding (LNC) schemes, called circular-shift LNC, whose encoding operations consist of only circular-shifts and bit-wise additions (XOR). Formulated as a special vector linear code over GF(2), an L-dimensional circular-shift linear code of degree δ restricts its local encoding kernels to be the summation of at most δ cyclic permutation matrices of size L. We show that on a general network, for a certain block length L, every scalar linear solution over GF(2 L−1 ) can induce an L-dimensional circular-shift linear solution with 1-bit redundancy per-edge transmission.Consequently, specific to a multicast network, such a circular-shift linear solution of an arbitrary degree δ can be efficiently constructed, which has an interesting complexity tradeoff between encoding and decoding with different choices of δ. By further proving that circular-shift LNC is insufficient to achieve the exact capacity of certain multicast networks, we show the optimality of the efficiently constructed circular-shift linear solution in the sense that its 1-bit redundancy is inevitable. Finally, both theoretical and numerical analysis imply that with increasing L, a randomly constructed circular-shift linear code has linear solvability behavior comparable to a randomly constructed permutation-based linear code, but has shorter overheads.

A redox reaction submerged by a high current magnitude is impressively observed in a Fe2O3 solid electrolyte-based resistive memory device at room temperature. Oxygen vacancy migration, Ag atom redox, phase-induced grain boundary, and water molecule interplay with the oxygen vacancy are responsible for the submerged redox behaviors. The observation of the submerged redox behavior in the Fe2O3 phase change process gives an insight into the evolution of memristors.

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Egg albumen is modified by hydrogen peroxide with concentrations of 5%, 10%, 15% and 30% at room temperature. Compared with devices without modification, a memory cell of Ag/10% HO-egg albumen/indium tin oxide exhibits obviously enhanced resistive switching memory behavior with a resistance ratio of 10, self-healing switching endurance for 900 cycles and a prolonged retention time for a 10 s @ 200 mV reading voltage after being bent 10 times. The breakage of massive protein chains occurs followed by the recombination of new protein chain networks due to the oxidation of amidogen and the synthesis of disulfide during the hydrogen peroxide modifying egg albumen. Ions such as Fe, Na, K, which are surrounded by protein chains, are exposed to the outside of protein chains to generate a series of traps during the egg albumen degeneration process. According to the fitting results of the double logarithm I-V curves and the current-sensing atomic force microscopy (CS-AFM) images of the ON and OFF states, the charge transfer from one trap center to its neighboring trap center is responsible for the resistive switching memory phenomena. The results of our work indicate that hydrogen- peroxide-modified egg albumen could open up a new avenue of biomaterial application in nanoelectronic systems.

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In this paper, band bending at an ITO−perovskite interface was proposed to fabricate highly efficient perovskite solar cells without electron or hole transport layers. Direct deposition of a perovskite (MAPbI 3-x Cl x ) on clean ITO results in downward shift of the band of the perovskite by about 170 meV at the ITO−perovskite interface, preventing holes from recombining with electrons collected in the ITO. The device without a dedicated electron transport layer or any modifications achieves a power conversion efficiency (PCE) of 17.42%. The band bending direction changes when a Sn−Pb mixed narrow band gap (1.21 eV) perovskite ((FASnI 3 ) 0.6 (MAPbI 3 ) 0.4 ) is used to replace MAPbI 3-x Cl x . An upward band shift of about 110 meV was observed at the ITO−perovskite interface, facilitating hole extraction while blocking electron transfer from the perovskite to ITO. Perovskite solar cells made from this narrow band gap Sn−Pb mixed perovskite achieves a PCE of 18.31%, the highest one without a hole transport layer among those in the known literature studies. Thus, band bending is proved to be an effective way to eliminate charge transport layers in perovskite solar cells.

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