Analysis of enhanced hole transport in naphthalene dicarboxyimide (NDI)-based n-type polymer field-effect transistors using solution-processed reduced graphene oxide electrodes

Ko, Museok,Lee, Yeoryang,Jo, Youngjoo,Jang, Jun Hyeok,Lee, Mi Jung Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.481 No.-

<P><B>Abstract</B></P> <P>In this study, organic field-effect transistors (OFETs) using a naphthalene dicarboxamide (NDI)-based n-type semiconducting polymer and electrodes comprising either Au or reduced graphene oxide (rGO) were fabricated. Compared with those with Au electrodes, transistors with rGO electrodes exhibited enhanced hole transport characteristics. The analysis of the interaction between the NDI-based polymer and the two electrodes revealed satisfactory hole transport in terms of device performance with the rGO electrode despite the less favorable work function for the injection of holes into the polymer semiconductor, corresponding to the formation of interfacial dipoles of different magnitudes. The electron orbital structure of the rGO electrode induced a smaller shift by the dipole moment at the interface between the electrode and semiconductor compared with that induced by the electron orbital structure of the gold electrode to promote ambipolarity. In both cases, energy barriers for the injection of charge at the interface were determined by ultraviolet photoelectron spectroscopy and Kelvin probe force microscopy analysis. In addition, a complementary logic inverter comprising two identical OFETs based on n-type NDI derivative and rGO electrodes with improved hole transport properties was fabricated.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Reduced graphene oxide electrodes enhance hole transport characteristics in n-type semiconducting polymer. </LI> <LI> Interfacial dipole measured by ultraviolet photoelecton spectroscopy to push-back effect of molecular orbitals. </LI> <LI> Complementary inverter was developed to prove the ambipolarity. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Enhanced hole transport in n-type semiconducting polymers with reduced graphene oxide contact electrode compared to that with gold electrode was analyzed.</P> <P>[DISPLAY OMISSION]</P>

Ambipolarity Factor of Tunneling Field-Effect Transistors (TFETs)

Jung-Shik Jang,Woo Young Choi 대한전자공학회 2011 Journal of semiconductor technology and science Vol.11 No.4

The ambipolar behavior of tunneling fieldeffect transistors (TFETs) has been investigated quantitatively by introducing a novel parameter: ambipolarity factor (ν). It has been found that the malfunction of TFET can result from the ambipolar state which is not on- or off- state. Therefore, the effect of ambipolar behavior on the device performance should be parameterized quantitatively, and this has been successfully evaluated as a function of device structure, gate oxide thickness, supply voltage, drain doping concentration and body doping concentration by using ν.

Ambipolarity Factor of Tunneling Field-Effect Transistors (TFETs)

Jang, Jung-Shik,Choi, Woo-Young The Institute of Electronics and Information Engin 2011 Journal of semiconductor technology and science Vol.11 No.4

The ambipolar behavior of tunneling field-effect transistors (TFETs) has been investigated quantitatively by introducing a novel parameter: ambipolarity factor (${\nu}$). It has been found that the malfunction of TFET can result from the ambipolar state which is not on- or off- state. Therefore, the effect of ambipolar behavior on the device performance should be parameterized quantitatively, and this has been successfully evaluated as a function of device structure, gate oxide thickness, supply voltage, drain doping concentration and body doping concentration by using ${\nu}$.

Inversion of Dominant Polarity in Ambipolar Polydiketopyrrolopyrrole with Thermally Removable Groups

Lee, Junghoon,Han, A‐,Reum,Hong, Jayeon,Seo, Jung Hwa,Oh, Joon Hak,Yang, Changduk WILEY‐VCH Verlag 2012 Advanced functional materials Vol.22 No.19

<P><B>Abstract</B></P><P>A narrow bandgap polymeric semiconductor, <B>BOC‐PTDPP</B>, comprising alkyl substituted diketopyrrolopyrrole (DPP) and <I>tert</I>‐butoxycarbonyl (<I>t</I>‐BOC)‐protected DPP, is synthesized and used in organic field‐effect transistors (OFETs). The polymer films are prepared by solution deposition and thermal annealing of precursors featuring thermally labile <I>t</I>‐BOC groups. The effects of the thermal cleavage on the molecular packing structure in the polymer thin films are investigated using thermogravimetric analysis (TGA), UV‐vis spectroscopy, atomic force microscopy (AFM), Fourier transform infrared (FT‐IR) spectroscopy, and X‐ray diffraction (XRD) analysis. Upon utilization of solution‐shearing process, integrating the ambipolar <B>BOC‐PTDPP</B> into transistors shows <I>p</I>‐channel dominant characteristics, resulting in hole and electron mobilities as high as 1.32 × 10<SUP>−2</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP> and 2.63 × 10<SUP>−3</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>, which are about one order of magnitude higher than those of the drop‐cast films. Very intriguingly, the dominant polarity of charge carriers changes from positive to negative after the thermal cleavage of <I>t</I>‐BOC groups at 200 °C. The solution‐sheared films upon subsequent thermal treatment show superior electron mobility (<I>μ</I><SUB>e</SUB> = 4.60 × 10<SUP>−2</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>), while the hole mobility decreases by one order of magnitude (<I>μ</I><SUB>h</SUB> = 4.30 × 10<SUP>−3</SUP> cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>). The inverter constructed with the combination of two identical ambipolar OFETs exhibits a gain of ∼10. Reported here for the first time is a viable approach to selectively tune dominant polarity of charge carriers in solution‐processed ambipolar OFETs, which highlights the electronically tunable ambipolarity of thermocleavable polymer by simple thermal treatment.</P>

Poly(diketopyrrolopyrrole‐benzothiadiazole) with Ambipolarity Approaching 100% Equivalency

Cho, Shinuk,Lee, Junghoon,Tong, Minghong,Seo, Jung Hwa,Yang, Changduk WILEY‐VCH Verlag 2011 Advanced Functional Materials Vol.21 No.10

<P><B>Abstract</B></P><P>As a characteristic feature of conventional conjugated polymers, it has been generally agreed that conjugated polymers exhibit either high hole transport property (p‐type) or high electron transport property (n‐type). Although ambipolar properties have been demonstrated from specially designed conjugated polymers, only a few examples have exhibited ambipolar transport properties under limited conditions. Furthermore, there is, as yet, no example with ‘equivalent’ hole and electron transport properties. We describe the realization of an equivalent ambipolar organic field‐effect transistor (FET) by using a single‐component visible–near infrared absorbing diketopyrrolopyrrole (DPP)‐benzothiadiazole (BTZ) copolymer, namely poly[3,6‐dithiene‐2‐yl‐2,5‐di(2‐decyltetradecyl)‐pyrrolo[3,4‐<I>c</I>]pyrrole‐1,4‐dione‐5’,5’’‐diyl‐<I>alt</I>‐benzo‐2,1, 3‐thiadiazol‐4,7‐diyl] (<B>PDTDPP‐<I>alt</I>‐BTZ</B>). <B>PDTDPP‐<I>alt</I>‐BTZ</B> shows not only ideally balanced charge carrier mobilities for both electrons (<I>▴<SUB>e</SUB></I> = 0.09 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP>) and holes (<I>▴<SUB>h</SUB></I> = 0.1 cm<SUP>2</SUP>V<SUP>−1</SUP>s<SUP>−1</SUP>) but also its inverter constructed with the combination of two identical ambipolar FETs exhibits a gain of ∼35 that is much higher than usually obtained values for unipolar logic.</P>

Remarkable Enhancement of Hole Transport in Top‐Gated N‐Type Polymer Field‐Effect Transistors by a High‐k Dielectric for Ambipolar Electronic Circuits

Baeg, Kang‐,Jun,Khim, Dongyoon,Jung, Soon‐,Won,Kang, Minji,You, In‐,Kyu,Kim, Dong‐,Yu,Facchetti, Antonio,Noh, Yong‐,Young WILEY‐VCH Verlag 2012 ADVANCED MATERIALS Vol.24 No.40

<P><B>A remarkable enhancement of p‐channel properties</B> is achieved in initially n‐channel dominant ambipolar P(NDI2OD‐T2) organic field‐effect transistors (OFETs) by the use of the fluorinated high‐k dielectric P(VDF‐TrFE). An almost two orders of magnitude increase in hole mobility (∼0.11 cm<SUP>2</SUP> V<SUP>−1</SUP> s<SUP>−1</SUP>) originates from a strong interface modification at the semiconductor/dielectric interface, which provides high‐performance complementary‐like inverters and ring oscillator circuits.</P>

Organic Complementary Circuits: Remarkable Enhancement of Hole Transport in Top‐Gated N‐Type Polymer Field‐Effect Transistors by a High‐k Dielectric for Ambipolar Electronic Circuits (Adv. Mater. 40/2012)

Baeg, Kang‐,Jun,Khim, Dongyoon,Jung, Soon‐,Won,Kang, Minji,You, In‐,Kyu,Kim, Dong‐,Yu,Facchetti, Antonio,Noh, Yong‐,Young WILEY‐VCH Verlag 2012 Advanced Materials Vol.24 No.40

<P>On page 5433, Yong‐Young Noh, Antonio Facchetti, Kang‐Jun Baeg, and co‐workers report that high performance ambipolar complementary inverters and ring oscillators are provided by a remarkable enhancement of both hole injection and transport for n‐channel dominant N2200 OFETs. The significant enhancement of hole mobility in N2200 OTFTs is attributed to the strong dipoles in fluorinated high‐k gate dielectric blend of P(VDF‐TrFE):PMMA. </P>

Charge Injection Engineering of Ambipolar Field-Effect Transistors for High-Performance Organic Complementary Circuits

Baeg, Kang-Jun,Kim, Juhwan,Khim, Dongyoon,Caironi, Mario,Kim, Dong-Yu,You, In-Kyu,Quinn, Jordan R.,Facchetti, Antonio,Noh, Yong-Young American Chemical Society 2011 ACS APPLIED MATERIALS & INTERFACES Vol.3 No.8

<P>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<SUP>2</SUP>/(Vs)) and n-channel (electron mobility ∼0.1–0.3 cm<SUP>2</SUP>/(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>I</I><SUB>off</SUB> < 70 nA when <I>I</I><SUB>on</SUB> > 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.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2011/aamick.2011.3.issue-8/am200705j/production/images/medium/am-2011-00705j_0009.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am200705j'>ACS Electronic Supporting Info</A></P>

Polarity Engineering of Conjugated Polymers by Variation of Chemical Linkages Connecting Conjugated Backbones

Yun, Hui-Jun,Choi, Hyun Ho,Kwon, Soon-Ki,Kim, Yun-Hi,Cho, Kilwon American Chemical Society 2015 ACS APPLIED MATERIALS & INTERFACES Vol.7 No.10

<P>The fine tuning of the dominant polarity in polymer semiconductors is a key issue for high-performance organic complementary circuits. In this paper, we demonstrate a new methodology for addressing this issue in terms of molecular design. In an alternating conjugated donor–acceptor copolymer system, we systematically engineered the chemical linkages that connect the aromatic units in donor moieties. Three donor moieties, thiophene–vinylene–thiophene (TVT), thiophene–acetylene–thiophene (TAT), and thiophene–cyanovinylene–thiophene (TCNT), were combined with an acceptor moiety, thienoisoindigo (TIID), and finally, three novel TIID-based copolymers were synthesized: PTIID–TVT, PTIID–TAT, and PTIID–TCNT. We found that the vinylene, acetylene, and cyanovinylene linkages decisively affect the energy structure, molecular orbital delocalization, microstructure, and, <I>most importantly</I>, the dominant polarity of the polymers. The vinylene-linked PTIID–TVT field-effect transistors (FETs) exhibited intrinsic hole and electron mobilities of 0.12 and 1.5 × 10<SUP>–3</SUP> cm<SUP>2</SUP> V<SUP>–1?</SUP>s<SUP>–1</SUP>, respectively. By contrast, the acetylene-linked PTIID–TAT FETs exhibited significantly improved intrinsic hole and electron mobilities of 0.38 and 0.03 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>, respectively. Interestingly, cyanovinylene-linked PTIID–TCNT FETs exhibited reverse polarity, with hole and electron mobilities of 0.07 and 0.19 cm<SUP>2</SUP> V<SUP>–1</SUP> s<SUP>–1</SUP>. As a result, the polarity balance, which is quantified as the electron/hole mobility ratio, was dramatically tuned from 0.01 to 2.7. Our finding demonstrates a new methodology for the molecular design of high-performance organic complementary circuits.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/aamick/2015/aamick.2015.7.issue-10/acsami.5b00073/production/images/medium/am-2015-00073f_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/am5b00073'>ACS Electronic Supporting Info</A></P>

Pd-YSZ cermet membranes with self-repairing capability in extreme H₂S conditions

Jeon, Sang-Yun,Singh, Bhupendra,Im, Ha-Ni,Lee, Kang-Taek,Song, Sun-Ju Elsevier 2017 CERAMICS INTERNATIONAL Vol.43 No.2

<P><B>Abstract</B></P> <P>A Pd-YSZ cermet membrane that performs coupled operations of hydrogen separation from a mixed-gas stream and simultaneous hydrogen production by non-galvanic water-splitting, and have high sulfur tolerance is fabricated. It is proved that in H<SUB>2</SUB>S containing atmosphere the Pd-YSZ membrane has self-repairing capability, originating mainly from the conversion of Pd<SUB>4</SUB>S back to metallic Pd and SO<SUB>2</SUB> by ambipolar-diffused oxygen obtained from water-splitting. The performance of membrane was analyzed at different temperatures in high H<SUB>2</SUB>S containing (0–4000ppmH<SUB>2</SUB>S) mixed gas feed during the operation as a hydrogen separation membrane as well as during the coupled operation of hydrogen separation and hydrogen production. At 900°C with the feed-stream having ≥2000ppmH<SUB>2</SUB>S, the hydrogen flux was severely affected due to the formation of some liquid phase of Pd<SUB>4</SUB>S, resulting in the segregation of hydrogen permeating Pd-phase at the membrane surface. But at 800°C, though the membrane was affected by the Pd<SUB>4</SUB>S formation in high H<SUB>2</SUB>S environment (up to 1200ppmH<SUB>2</SUB>S), its self-repairing capability and additional hydrogen production by water-splitting is capable of maintaining the hydrogen flux around ~1.24cm<SUP>3</SUP> (STP)/min.cm<SUP>2</SUP>, a value expected by the same membrane while performing only the hydrogen separation function in H<SUB>2</SUB>S-free environment.</P>