{"id":1514,"date":"2015-06-23T03:24:01","date_gmt":"2015-06-23T03:24:01","guid":{"rendered":"http:\/\/chemweb.unl.edu\/sinitskii\/?p=1514"},"modified":"2017-10-25T16:05:24","modified_gmt":"2017-10-25T16:05:24","slug":"tis3-unl-news","status":"publish","type":"post","link":"http:\/\/chemweb.unl.edu\/sinitskii\/tis3-unl-news\/","title":{"rendered":"[UNL News] New 2-D material\u2019s properties show promise"},"content":{"rendered":"
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\n[UNL chemists: New 2-D material\u2019s properties show promise<\/em> | University Communications | 6\/23\/2015]
\nOne completed a series of theoretical calculations to predict its properties with the help of a massive computing center. The other grew it in bulk before waxing its atom-thin whiskers with the assistance of adhesive tape.<\/p>\n

Together, University of Nebraska-Lincoln chemists Xiao Cheng Zeng<\/a> and Alexander Sinitskii<\/a> have demonstrated that a compound called titanium trisulfide could surge toward the fore of two-dimensional materials that are gaining popularity among designers of microelectronics.<\/p>\n

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Photo by: Craig Chandler | University Communications<\/em><\/p>\n<\/div>\n

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The rise of 2-D materials \u2013 sheets no more than a few atoms thick \u2013 began with the 2004 demonstration of graphene, which remains the strongest and thinnest material known.<\/p>\n

Zeng and Sinitskii have published two recent studies showing that titanium trisulfide compares favorably not only with graphene, but also phosphorene and molybdenum disulfide \u2013 fellow 2-D materials that have shown great promise for electronic applications.<\/p>\n

\u201cThere was no interest in the properties of few-layer titanium trisulfide until now,\u201d said Zeng, an Ameritas University Professor of chemistry. \u201cWe were among the first to look at them, and we\u2019ve been very excited by what we\u2019ve seen.\u201d<\/p>\n

Zeng\u2019s theoretical study revealed that 2-D titanium trisulfide has the potential to transport electrons faster than phosphorene and molybdenum disulfide. This \u201celectron mobility\u201d helps dictate the speed of transistors, the devices that control electric current and amplify electrical power in technology ranging from cellphones to spacecraft.<\/p>\n

Transistors also form the core of semiconductors, which rapidly switch between a current-conducting \u201con\u201d state and current-insulating \u201coff\u201d state to represent the 1s and 0s of digital computing.<\/p>\n

Graphene boasts unparalleled conductivity, but crucially lacks the quality that can turn it off: a band gap, which describes the energy necessary for electrons to jump from their near orbits around atoms to an outer \u201cconduction band\u201d that promotes conductivity.<\/p>\n

Zeng and Sinitskii found that titanium trisulfide has a moderate band gap that approximates the one found in semiconductor favorite silicon, making it ideal for the on\/off switching prized in such devices. The material also yields a large disparity between \u201con\u201d and \u201coff\u201d conditions, which helps distinguish between resulting 1s and 0s.<\/p>\n

The material\u2019s band gap also allows it to absorb elementary particles of light known as photons from most of the sun\u2019s emission spectrum. Because of this, titanium trisulfide could also prove useful in solar-cell designs, Sinitskii said.<\/p>\n

Sinitskii, an assistant professor of chemistry, followed up on Zeng\u2019s theoretical calculations by combining titanium and sulfur to form a block of titanium trisulfide. He then used adhesive tape to rip off microscopic whiskers of the compound in the same way that the pioneers of graphene did with graphite more than a decade ago.<\/p>\n

Sinitskii turned those whiskers into transistors and directed the performance tests that confirmed his colleague\u2019s work.<\/p>\n

\u201cAs a theoretician, I always want to predict something,\u201d Zeng said. \u201cThe dream for us is that somebody makes it in the laboratory.<\/p>\n

\u201cI couldn\u2019t help but tell Alex. He\u2019s one of the leading experts in the world when it comes to making two-dimensional materials, and he did it just a couple of months after (I asked him).\u201d<\/p>\n

Sinitskii said the 2-D predecessors of titanium trisulfide should help accelerate his team\u2019s efforts to study and improve it.<\/p>\n

\u201cWhen people started working with devices based on graphene, the first two-dimensional material, everything was new,\u201d he said. \u201cResearchers studied how different parameters affect device performance. When they started working on other 2-D materials, the knowledge generated from graphene research was very useful.<\/p>\n

\u201cIn our case, we\u2019re actually in quite a good position, because we can learn a lot from those earlier studies and apply prior knowledge to making better transistors from titanium trisulfide.\u201d<\/p>\n

Zeng\u2019s recent study, published in the journal Angewandte Chemie International Edition<\/a>, was co-authored with postdoctoral researcher Jun Dai. The researchers performed their calculations through UNL\u2019s Holland Computing Center.<\/p>\n

The Sinitskii-led study appeared in the journal Nanoscale<\/a>. He shared authorship with postdoctoral researcher Alexey Lipatov and graduate students Peter Wilson, Mikhail Shekhirev, Jacob Teeter and Ross Netusil.<\/p>\n

Both research teams received support from UNL\u2019s Materials Research Science and Engineering Center<\/a>, part of a nationwide network of MRSECs sponsored by the National Science Foundation. They conducted their work in conjunction with the Nebraska Center for Materials and Nanoscience.<\/p>\n

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Written by: Scott Schrage | University Communications
\nPhoto by: Craig Chandler | University Communications<\/p>\n

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