High performance ambipolar organic mixed ionic-electronic conductor for adaptive logic circuits and neuromorphic electronics

Organic mixed ionic-electronic conductors (OMIECs) are central to bioelectronic applications such as biosensors, health monitoring devices and neural interfaces, and have facilitated efficient next-generation brain-inspired computing and biohybrid systems. Most OMIECs are hole-conducting (p-type) materials, while complimentary logic circuits and various biosensors require electron-conducting (n-type) materials too. Here we show an ambipolar mixed ionic-electronic polymer that achieves high on/off ratios with high ambient p- and n- type stability. We highlight the versatility of the material by demonstrating its use as a neuromorphic memory element, an adaptable ambipolar complementary logic inverter, and a neurotransmitter sensor. The ambipolar operation of this material allows for straightforward monolithic fabrication and integration, and opens a route towards more sophisticated complex logic and adaptive circuits.

Surface and Bulk Oxygen Kinetics of BaCo0.4Fe0.4Zr0.2−XYXO3−δ Triple Conducting Electrode Materials

Triple ionic-electronic conductors have received much attention as electrode materials. In this work, the bulk characteristics of oxygen diffusion and surface exchange were determined for the triple-conducting BaCo0.4Fe0.4Zr0.2−XYXO3−δ suite of samples. Y substitution increased the overall size of the lattice due to dopant ionic radius and the concomitant formation of oxygen vacancies. Oxygen permeation measurements exhibited a three-fold decrease in oxygen permeation flux with increasing Y substitution. The DC total conductivity exhibited a similar decrease with increasing Y substitution. These relatively small changes are coupled with an order of magnitude increase in surface exchange rates from Zr-doped to Y-doped samples as observed by conductivity relaxation experiments. The results indicate that Y-doping inhibits bulk O2− conduction while improving the oxygen reduction surface reaction, suggesting better electrode performance for proton-conducting systems with greater Y substitution.

Structural, optical and electrical properties of Mn-doped ZnFe2O4 synthesized using sol-gel method

Samples with doping of Mn (0, 2, and 4%) in ZnFe2O4 were prepared by sol-gel chemical route at 80oC. X-ray powder diffraction and Raman spectrum analysis were used to determine the preliminary phase of obtained samples. W-H and SSP plots were used to determine the crystallite size and micro-strain of samples. Using zeta potential and scanning electron microscope, the surface charge and morphology of the prepared samples were studied. The optical bandgap of sample suggested that it was semiconducting. The dielectric characteristics of samples were examined as a function of temperature at various frequencies (1 KHz, 10 KHz, 100 KHz, and 1 MHz) (60-600oC). Dielectric study revealed the presence of interfacial and orientational polarization, with dielectric constants and dissipation factors ranging from (0.7–460) to (0.3–0.8), remain thermally stability up to 300oC. In samples ZF-0, ZF-2, and ZF-4, the thermal dependence of DC conductivity demonstrates Arrhenius transport with one, two, and three regions of conduction, respectively. The sources of charge carrier in samples were Vo,e1 defects (Vo - 2FE2+ Fe3+') and (2M3+ Zn2+ - 2FE2+ Fe3+'). The current work could help identify possible applications in semiconductor devices, thermally stable capacitors, and as mixed ionic electronic conductors in solid oxide fuel cells.