High Speeds Complementary Integrated Circuits Fabricated with All-Printed Polymeric Semiconductors Kang-Jun Baeg, 1,2 Dongyoon Khim, 1 Dong-Yu Kim, 1 Soon-Won Jung, 2 Jae Bon Koo, 2 In-Kyu You, 2 Henry Yan, 3 Antonio Facchetti, 3 Yong-Young Noh 2,4 1 Heeger Center for Advanced Materials, Department of Nanobio Materials and Electronics, Gwangju Institute of Science and Technology (GIST), 261 Cheomdan-gwagiro, Buk-gu, Gwangju 500-712, Republic of Korea 2 Convergence Components and Materials Research Laboratory, Electronics and Telecommunications Research Institute (ETRI), 161 Gajeong-dong, Yuseong-gu, Daejeon 305-350, Republic of Korea 3 Polyera Corporation, 8045 Lamon Avenue Skokie, IL 60077 4 Department of Chemical Engineering, Hanbat National University, San 16-1, Dukmyung-dong, Yuseong-gu, Daejeon 305-719, Republic of Korea Correspondence to: Y.-Y. Noh (E-mail: yynoh@hanbat.ac.kr) or D.-Y. Kim (E-mail: kimdy@gist.ac.kr) or A. Facchetti (E-mail: afacchetti@polyera.com) Received 16 August 2010; revised 16 August 2010; accepted 16 August 2010; published online 24 September 2010 DOI: 10.1002/polb.22148 ABSTRACT: Inkjet-printed high speed polymeric complementary circuits are fabricated using an n-type ([poly{[N,N 0 -bis(2-octyldo- decyl)-naphthalene-1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5 0 -(2,2 0 - dithiophene)} [P(NDI2OD-T2), Polyera ActivInk N2200] and two p- type polymers [poly(3-hexylthiophene) (P3HT) and a dithiophene- based polymer (Polyera ActivInk P2100)]. The top-gate/bottom- contact (TG/BC) organic field-effect transistors (OFETs) exhibit well-balanced and very-high hole and electron mobilities (l FET ) of 0.2–0.5 cm 2 /Vs, which were enabled by optimization of the inkjet- printed active features, small contact resistance both of electron and hole injections, and effective control over gate dielectrics and its orthogonal solvent effect (selection of poly(methyl methacry- late) and 2-ethoxyethanol). Our first demonstrated inkjet-printed polymeric complementary devices have been integrated to high- performance complementary inverters (gain >30) and ring oscilla- tors (oscillation frequency 50 kHz). We believe that the operating frequency of printable organic circuits can be further improved more than 10 MHz by fine-tuning of the device architecture and optimization of the p- and n-channel semiconductor processing. V C 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 62–67, 2011 KEYWORDS: flexible electronics; inkjet printing; organic elec- tronics; organic field-effect transistors INTRODUCTION Complementary metal–oxide–semiconductor (CMOS) inverters are key building blocks for several digital or analog integrated circuits and are considered particularly suitable for organic electronic applications. 1–4 CMOS inverters, which are composed of both p-type and n-type field-effect transistors (FETs), exhibit higher noise immunity and lower static power consumption than single polarity-based inver- ters. Several important studies have addressed the fabrication of organic inverters and ring oscillators. 5–12 Most of these devices were unipolar (typically p-type) or based on vapor- deposited films of molecular semiconductors. These organic integrated circuits showed impressive operation frequencies ranging from a few hundred Hz (typically for solution- processed semiconductors) 11,12 to a few tens of kHz (for vapor-deposited semiconductors). 5 The performances of these circuits are limited by the combination of low field-effect mobilities of the organic semiconductors, unipolar circuit architecture, long channel lengths, and large overlap capaci- tance between the gate to the source/drain (S/D) electrodes. Therefore, to enhance circuit speeds, it is first necessary to de- velop an integrated CMOS circuit architecture with high elec- tron and hole mobility semiconductors. Furthermore, these or- ganic integrated devices should also be fabricable in ambient using inexpensive graphic art printing techniques. Few studies developed complementary inverters using gravure and inkjet- printing. 13,14 However, to the best of our knowledge, inkjet- printed monolithically integrated polymeric complementary circuits operating in ambient have never been demonstrated. Inkjet printing is a cost-effective method to fabricate micro scale-patterned regions. 15 The direct-write ability of the ink- jet printing process removes the need for masks leading to decreased device manufacturing complexity, material waste, and cross contamination. 15–17 To realize high performance complementary circuits by inkjet printing, both n-type and Additional Supporting Information may be found in the online version of this article. V C 2010 Wiley Periodicals, Inc. 62 JOURNAL OF POLYMER SCIENCE: PART B: POLYMER PHYSICS 2011, 49, 62–67 FULL PAPER WWW.POLYMERPHYSICS.ORG