Electrodeposited, Transverse Nanowire Electroluminescent Junctions

Shaopeng Qiao, Qiang Xu, Rajen K. Dutta, Mya Le Thai, Xiaowei Li, and Reginald M. Penner*
ACS Nano (2016) ASAP.10.1021/acsnano.6b04022

Shaopeng has discovered a means for electrodepositing and characterizing the electroluminescence (EL) properties of linear arrays of many nearly identical metal-semiconductor-metal junctions. In this paper, he uses this platform to characterize arrays of nickel-(nc-CdSe)-gold M-S-M junctions. These junctions are prepared by first electrodepositing an ensemble of 60 nearly identical nc-CdSe nanowires, and then locating nickel and gold contacts on opposite sides of each nanowire along their axes also using electrodeposition. These devices are termed "transverse nanowire electroluminescent junctions" and they are surprisingly efficient.

100k Cycles and Beyond: Extraordinary Cycle Stability for MnO2 Nanowires Imparted by a Gel Electrolyte

Mya Le Thai, Girija Thesma Chandran, Rajen Dutta, Xiaowei Li, and Reginald M. Penner*
ACS Energy Letters 1 (2016) 57.10.1021/acsenergylett.6b00029

The problem with using nanowires as energy storage materials is their limited cycle stability. Nanowires are susceptible to dissolution and corrosion which rapidly cause a loss of through-wire conduction and irreversible capacity loss. Mya discovered that in the case of MnO2 - an Li+ insertion metal oxide - substituting a liquid electrolyte based on acetonitrile or propylene carbonate (PC) with a viscous PMMA-containing PC electrolyte extends the cycle stability of these nanowires from 5000 cycles to more than 100,000 cycles.

Lithographically Patterned PEDOT Nanowires for the Detection of Iron(III) with Nanomolar Sensitivity

Lindsay R. Kindra, Crystin J. Eggers, Andrew T. Liu, Kelly Mendoza, Jennifer Mendoza, Aviva R. Klein Myers, and Reginald M. Penner*
Analytical Chemistry 87 (2015) 11492.10.1021/acs.analchem.5b03255

Lindsay and coworkers describe the preparation and properties of DFA-doped PEDOT films and nanowires for the detection of Fe(III) in high ionic-strength aqueous solutions. An array of 200 PEDOT-DFA nanowires is far superior for this purpose, relative to a film, enabling the detection of Fe(III) across the range from [Fe(III)] = 10-7 to 10-4 M. A limit of detection is estimated to be 340 pM. The sensitivity of these nanowire arrays for Fe(III) is superior to that provided by ISEs and all other electrical-based sensors, including chemFETs and other types of chemiresistors.

A 30 micron Coaxial Nanowire Photoconductor Enabling Orthogonal Carrier Collection

Qiang Xu, Shaopeng Qiao, Rajen Dutta, Zhengyun Wu, and Reginald M. Penner*
Nano Letters 15 (2015) 5861.10.1021/acs.nanolett.5b01941

The bandwidth and sensitivity of photoconductors increases as the distance between the electrical contacts decreases. This is bad since increasing the performance of the photodetector, requires that the photoactive area of the detector be diminished. Qiang envisioned a new architecture for a photoconductive nanowire in which the electrical contacts are an integral part of the nanowire. This enables the photoactive area to be decoupled from the electrical pathlength in the absorber material (CdSe in this case). Qiang is able to achieve excellent metrics for light detection including a photoconductive gain of 2200, a photocurrent response and recovery times of 10 and 100 microseconds, respectively, and a responsivity of 209 A/W.

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© 2016, Reginald M. Penner