{"63912":{"#nid":"63912","#data":{"type":"news","title":"New Transistor for Plastic Electronics Exhibits the Best of Both Worlds","body":[{"value":"\u003Cp\u003EIn the quest to develop flexible plastic electronics, one of\nthe stumbling blocks has been creating transistors with enough stability for\nthem to function in a variety of environments while still maintaining the\ncurrent needed to power the devices. Online in the journal \u003Cem\u003EAdvanced Materials,\u003C\/em\u003E researchers from the Georgia Institute of\nTechnology describe a new method of combining top-gate organic field-effect\ntransistors with a bilayer gate insulator. This allows the transistor to\nperform with incredible stability while exhibiting good current performance. In\naddition, the transistor can be mass produced in a regular atmosphere and can\nbe created using lower temperatures, making it compatible with the plastic\ndevices it will power.\u003C\/p\u003E\n\n\n\n\u003Cp\u003EThe research team used an existing semiconductor and changed\nthe gate dielectric because transistor performance depends not only on the\nsemiconductor itself, but also on the interface between the semiconductor and\nthe gate dielectric. \u003C\/p\u003E\n\n\n\n\u003Cp\u003E\u201cRather than using a single dielectric material, as many\nhave done in the past, we developed a bilayer gate dielectric,\u201d said Bernard\nKippelen, director of the Center for Organic Photonics and Electronics and\nprofessor in Georgia Tech\u2019s School of Electrical and Computer Engineering. \u003C\/p\u003E\n\n\n\n\u003Cp\u003EThe bilayer dielectric is made of a fluorinated polymer\nknown as CYTOP and a high-\u003Cem\u003Ek\u003C\/em\u003E\nmetal-oxide layer created by atomic layer deposition. Used alone, each\nsubstance has its benefits and its drawbacks. \u003C\/p\u003E\n\n\n\n\u003Cp\u003ECYTOP is known to form few defects at the interface of the\norganic semiconductor, but it also has a very low dielectric constant, which\nrequires an increase in drive voltage. The high-\u003Cem\u003Ek\u003C\/em\u003E metal-oxide uses low voltage, but doesn\u2019t have good stability\nbecause of a high number of defects on the interface. \u003C\/p\u003E\n\n\n\n\u003Cp\u003ESo, Kippelen and his team wondered what would happen if they\ncombined the two substances in a bilayer. Would the drawbacks cancel each other\nout? \u003C\/p\u003E\n\n\n\n\u003Cp\u003E\u201cWhen we started to do the test experiments, the results\nwere stunning. We were expecting good stability, but not to the point of having\nno degradation in mobility for more than a year,\u201d said Kippelen.\u003C\/p\u003E\n\n\n\n\n\n\u003Cp\u003EThe team performed a battery of tests to see just how stable\nthe bilayer was. They cycled the transistors 20,000 times. There was no\ndegradation. They tested it under a continuous bias stress where they ran the\nhighest possible current through it. There was no degradation. They even stuck\nit in a plasma chamber for five minutes. There was still no degradation. \u003C\/p\u003E\n\n\u003Cp\u003EThe only time they saw any degradation was when they dropped\nit into acetone for an hour. There was some degradation, but the transistor was\nstill operational. \u003C\/p\u003E\n\n\n\n\u003Cp\u003ENo one was more surprised than Kippelen. \u003C\/p\u003E\n\n\n\n\u003Cp\u003E\u201cI had always questioned the concept of having air-stable\nfield-effect transistors, because I thought you would always have to combine\nthe transistors with some barrier coating to protect them from oxygen and\nmoisture. We\u2019ve proven ourselves wrong through this work,\u201d said Kippelen.\u003C\/p\u003E\n\n\n\n\u003Cp\u003E\u201cBy having the bilayer gate insulator we have two different\ndegradation mechanisms that happen at the same time, but the effects are such\nthat they compensate for one another,\u201d explains Kippelen.\u0026nbsp; \u201cSo if you use one it leads to a decrease of\nthe current, if you use the other it leads to a shift of the thereshold voltage\nand over time to an increase of the current. But if you combine them, their\neffects cancel out.\u201d\u003C\/p\u003E\n\n\n\n\u003Cp\u003E\u201cThis is an elegant way of solving the problem. So, rather\nthan trying to remove each effect, we took two processes that complement one\nanother and as a result you have a transistor that\u2019s rock stable.\u201d\u003C\/p\u003E\n\n\n\n\u003Cp\u003EThe transistor conducts current and runs at a voltage\ncomparable to amorphous silicon, the current industry standard used on glass\nsubstrates, but can be manufactured at temperatures below 150\u003Cstrong\u003E\u00b0\u003C\/strong\u003EC, in line with the capabilities of plastic\nsubstrates. It can also be created in a regular atmosphere, making it easier to\nfabricate than other transistors. \u003C\/p\u003E\n\n\n\n\u003Cp\u003EApplications for these transistors include smart bandages,\nRFID tags, plastic solar cells, light emitters for smart cards \u2013 virtually any\napplication where stable power and a flexible surface are needed. \u003C\/p\u003E\n\n\n\n\u003Cp\u003EIn this paper the tests were performed on glass\nsubstrates.\u0026nbsp; Next, the team plans on\ndemonstrating the transistors on flexible plastic substrates. Then they will\ntest the ability to manufacture the bilayer transistors with ink jet printing\ntechnologies. \u003C\/p\u003E\n\n\n\n\u003Cp\u003E\u003Cem\u003EKippelen\u2019s research\nteam was comprised of Do Kyung Hwang, Canek Fuentes-Hernandez, Jungbae Kim,\nWilliam J. Postcavage Jr. and Sung-Jin Kim.\u003C\/em\u003E\u003C\/p\u003E\n\n\n\n\u003Cp\u003E\u003Cem\u003EThe research was\nsupported by Solvay, the Office of Naval Research and the National Science\nFoundation.\u003C\/em\u003E\u003C\/p\u003E","summary":null,"format":"limited_html"}],"field_subtitle":"","field_summary":[{"value":"\u003Cp\u003EBernard Kippelen and his research team at the Center for Organic Photonics and Electronics have developed a transistor with excellent stability and performance for use on plastic electronics.\u003C\/p\u003E","format":"limited_html"}],"field_summary_sentence":[{"value":"COPE develops transistor with excellent stability and performance for use on plastic electronics."}],"uid":"27310","created_gmt":"2011-01-27 09:28:44","changed_gmt":"2016-10-08 03:08:06","author":"David Terraso","boilerplate_text":"","field_publication":"","field_article_url":"","dateline":{"date":"2011-01-27T00:00:00-05:00","iso_date":"2011-01-27T00:00:00-05:00","tz":"America\/New_York"},"extras":[],"hg_media":{"63911":{"id":"63911","type":"image","title":"Top-Gate Organic Field-Effect Transistor with Bilayer Gate Insulator","body":null,"created":"1449176708","gmt_created":"2015-12-03 21:05:08","changed":"1475894561","gmt_changed":"2016-10-08 02:42:41","alt":"Top-Gate Organic Field-Effect Transistor with Bilayer Gate Insulator","file":{"fid":"191894","name":"TiPs-bilayer-flexible_OFETs.JPG","image_path":"\/sites\/default\/files\/images\/TiPs-bilayer-flexible_OFETs_0.JPG","image_full_path":"http:\/\/hg.gatech.edu\/\/sites\/default\/files\/images\/TiPs-bilayer-flexible_OFETs_0.JPG","mime":"image\/jpeg","size":572142,"path_740":"http:\/\/hg.gatech.edu\/sites\/default\/files\/styles\/740xx_scale\/public\/images\/TiPs-bilayer-flexible_OFETs_0.JPG?itok=yKAgrElI"}}},"media_ids":["63911"],"groups":[{"id":"1183","name":"Home"}],"categories":[{"id":"145","name":"Engineering"}],"keywords":[{"id":"2431","name":"Bernard Kippelen"},{"id":"10797","name":"center for organic photonics and electronics"},{"id":"594","name":"college of engineering"},{"id":"609","name":"electronics"},{"id":"2942","name":"Kippelen"},{"id":"2289","name":"organic"},{"id":"11765","name":"plastic electronics"},{"id":"166855","name":"School of Electrical and Computer Engineering"},{"id":"4261","name":"transistor"}],"core_research_areas":[],"news_room_topics":[],"event_categories":[],"invited_audience":[],"affiliations":[],"classification":[],"areas_of_expertise":[],"news_and_recent_appearances":[],"phone":[],"contact":[{"value":"\u003Cp\u003E\u003Cstrong\u003EGeorgia Tech Media Relations\u003C\/strong\u003E\u003Cbr \/\u003ELaura Diamond\u003Cbr \/\u003E\u003Ca href=\u0022mailto:laura.diamond@comm.gatech.edu\u0022\u003Elaura.diamond@comm.gatech.edu\u003C\/a\u003E\u003Cbr \/\u003E404-894-6016\u003Cbr \/\u003EJason Maderer\u003Cbr \/\u003E\u003Ca href=\u0022mailto:maderer@gatech.edu\u0022\u003Emaderer@gatech.edu\u003C\/a\u003E\u003Cbr \/\u003E404-660-2926\u003C\/p\u003E","format":"limited_html"}],"email":["david.terraso@comm.gatech.edu"],"slides":[],"orientation":[],"userdata":""}}}