Pentacene integrated thin-film transistors and circuits

Organic semiconductors offer the potential of large-area, mechanically flexible electronics due to their low processing temperatures. We have developed a near-room-temperature (< 95°C) process flow to fabricate pentacene integrated organic thin-film transistors (OTFTs) compatible with plastic substrates such as polyethylene terephthalate (PET). Integration of inkjet printed organic photoconductors (OPDs) based on titanyl pthalocyanine with OTFTs is demonstrated for the first time in an integrated process. Using the OTFT as a switch in series with an OPD, a pixel circuit was designed and measured, in addition to a proof-of-concept 4x4 active matrix imager. The individual pixels were measured to have a responsivity of 6x10-5 A/W, and a pixel on/off conductance ratio of 880, both at an irradiance of 5 mW/cm 2. The imager uses a 25 V power supply and was shown to correctly image a "T" pattern after 1st order calibration. A model for the current-voltage characteristics based upon amorphous silicon models was implemented in MATLAB to investigate design trade-offs in organic digital circuits. A dual threshold voltage process is suggested to enable area-efficient zero-VGS current sources. The area and power savings of this approach is discussed compared to a single VT process. We also motivate the necessity for lowering the power supply, both for area savings and improvement in circuit lifetime due to reduction in bias stress effects. A process flow for a dual VT OTFT technology, enabled using two gate metals, is presented. By using a low work function metal (aluminum) and a high work function metal (platinum), we can obtain two threshold voltage devices.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2009

Author dc:creator

• Nausieda, Ivan Alexander

Advisor dc:contributor.advisor

• Charles G. Sodini.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/55119

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/55119