title: Charge injection engineering of ambipolar field-effect transistors for high-performance organic complementary circuits.
abstract: Ambipolar π-conjugated polymers may provide inexpensive large-area manufacturing of complementary integrated circuits (CICs) without requiring micro-patterning of the individual p- and n-channel semiconductors. However, current-generation ambipolar semiconductor-based CICs suffer from higher static power consumption, low operation frequencies, and degraded noise margins compared to complementary logics based on unipolar p- and n-channel organic field-effect transistors (OFETs). Here, we demonstrate a simple methodology to control charge injection and transport in ambipolar OFETs via engineering of the electrical contacts. Solution-processed caesium (Cs) salts, as electron-injection and hole-blocking layers at the interface between semiconductors and charge injection electrodes, significantly decrease the gold (Au) work function (∼4.1 eV) compared to that of a pristine Au electrode (∼4.7 eV). By controlling the electrode surface chemistry, excellent p-channel (hole mobility ∼0.1-0.6 cm(2)/(Vs)) and n-channel (electron mobility ∼0.1-0.3 cm(2)/(Vs)) OFET characteristics with the same semiconductor are demonstrated. Most importantly, in these OFETs the counterpart charge carrier currents are highly suppressed for depletion mode operation (I(off) < 70 nA when I(on) > 0.1-0.2 mA). Thus, high-performance, truly complementary inverters (high gain >50 and high noise margin >75% of ideal value) and ring oscillators (oscillation frequency ∼12 kHz) based on a solution-processed ambipolar polymer are demonstrated.
authors.affiliation: Department of Chemical Engineering, Hanbat National University, San 16-1, Dukmyung-dong, Yuseong-gu, Daejeon 305-719, Republic of Korea. kangjun100@etri.re.kr
authors.forename: Kang-Jun
authors.initials: KJ
authors.lastname: Baeg
authors.forename: Juhwan
authors.initials: J
authors.lastname: Kim
authors.forename: Dongyoon
authors.initials: D
authors.lastname: Khim
authors.forename: Mario
authors.initials: M
authors.lastname: Caironi
authors.forename: Dong-Yu
authors.initials: DY
authors.lastname: Kim
authors.forename: In-Kyu
authors.initials: IK
authors.lastname: You
authors.forename: Jordan R
authors.initials: JR
authors.lastname: Quinn
authors.forename: Antonio
authors.initials: A
authors.lastname: Facchetti
authors.forename: Yong-Young
authors.initials: YY
authors.lastname: Noh
mesh_terms: D002254:Carbonates / Q000737:chemistry; D002586:Cesium / Q000737:chemistry; D004566:Electrodes; D006046:Gold / Q000737:chemistry; D018625:Microscopy, Atomic Force; D009930:Organic Chemicals / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D014173:Transistors, Electronic
chemical_list: D002254:Carbonates; D009930:Organic Chemicals; D011108:Polymers; D002586:Cesium; D006046:Gold; C545311:cesium carbonate