p-Type Organic Semiconductor: Soluble DNTT Precursor

Printed Electronics (PE) is an attractive technology for fabricating electronic circuits in a low-cost and efficient manner by printing. Flexible-sensor, -display, -solar cell and so on are possible to realize by printing these devices on flexible substrates such as plastic film or paper. High performance soluble organic semiconductors are required for the fabrication of circuits in PE.

Dinaphtho[2,3-b:2',3'-f]thieno[3,2-b]thiophene (DNTT) developed by Takimiya is widely used as an air stable and high performance p-type organic semiconducting material.¹⁾ DNTT is insoluble in common organic solvents which makes fabrication of DNTT-based devices in a solution process difficult. To overcome this limitation, DNTT-PMIs [endo-DNTT-PMI (1) and exo-DNTT-PMI (2)] were developed.

DNTT-PMIs are convertible to DNTT by heating at 200 °C along with elimination of an N-phenylmaleimide (PMI) moiety.

A DNTT thin film is successfully fabricated by coating DNTT-PMIs on a substrate followed by heating. As an actual application of DNTT-PMIs, fabrications of organic transistors and nonvolatile memories have been reported.²⁾

Performances of organic field-effect transistors fabricated by using our products of DNTT-PMIs were evaluated under the cooperation of TEIJIN LIMITED, and found that each DNTT-PMI-based device showed high career mobilities (exo-DNTT-PMI: μ_max = 2.33 cm²/Vs, endo-DNTT-PMI: μ_max = 1.18 cm²/Vs).