Publications

Highlights from HEROIC publications

  • Ambipolar charge distribution in donor–acceptor polymer field-effect transistors
  • Direct-written polymer field-effect transistors operating at 20 MHz
  • Inkjet Printed Single-Walled Carbon Nanotube Based Ambipolar and Unipolar Transistors for High-Performance Complementary Logic Circuits
  • Macroscopic and high-throughput printing of aligned nanostructured polymer semiconductors for MHz large-area electronics
  • Injection Length in Staggered Organic Thin Film Transistors:  Assessment and Implications for Device Downscaling
  • High-Mobility Naphthalene Diimide and Selenophene-Vinylene-Selenophene-Based Conjugated Polymer: n-Channel Organic Field-Effect Transistors and Structure–Property Relationship
  • Ambipolar charge distribution in donor–acceptor polymer field-effect transistors

    Journal of Materials Chemistry C (2016)

    Xin Yu Chin, Giuseppina Pace, Cesare Soci and Mario Caironi

    Recent developments in the design and synthesis of donor–acceptor semiconducting copolymers have significantly contributed to improve the ambipolar transport properties of polymer field-effect transistors (FETs). The further development of such FETs towards real applications would greatly benefit from the knowledge of the specific charge distribution along the channel, especially in the ambipolar regime. Here we accomplish this task by adopting charge modulation spectroscopy (CMS) and microscopy (CMM), electro-optical spectroscopy techniques which allow us to probe in situ charge induced features in the transmission spectra of conjugated polymers, to study a model high mobility donor–acceptor co-polymer (DPPT-TT, poly(N-alkyldiketopyrrolo-pyrrole dithienylthieno[3,2-b]thiophene)). Thanks to the sub-micrometer spatial resolution of confocal microscopy, we are able to isolate the specific contribution of channel and electrode regions which are superimposed in the macroscopic CMS spectra, thus allowing the mapping of hole and electron distributions across the active channel in both unipolar and ambipolar operating regimes. Our findings illustrate the use of a local probe in charge-modulation experiments to correctly assign spectral features and to determine the distributions of positive and negative charge carriers in an operating device, which has relevant implications on the understanding of the nature of charge transport in high-mobility ambipolar semiconducting polymers.

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  • Direct-written polymer field-effect transistors operating at 20 MHz

    Scientific Report (2016)

    Andrea Perinot, Prakash Kshirsagar, Maria Ada Malvindi, Pier Paolo Pompa, Roberto Fiammengo and Mario Caironi

    Printed polymer electronics has held for long the promise of revolutionizing technology by delivering distributed, flexible, lightweight and cost-effective applications for wearables, healthcare, diagnostic, automation and portable devices. While impressive progresses have been registered in terms of organic semiconductors mobility, field-effect transistors (FETs), the basic building block of any circuit, are still showing limited speed of operation, thus limiting their real applicability. So far, attempts with organic FETs to achieve the tens of MHz regime, a threshold for many applications comprising the driving of high resolution displays, have relied on the adoption of sophisticated lithographic techniques and/or complex architectures, undermining the whole concept. In this work we demonstrate polymer FETs which can operate up to 20 MHz and are fabricated by means only of scalable printing techniques and direct-writing methods with a completely mask-less procedure. This is achieved by combining a fs-laser process for the sintering of high resolution metal electrodes, thus easily achieving micron-scale channels with reduced parasitism down to 0.19 pF mm−1, and a large area coating technique of a high mobility polymer semiconductor, according to a simple and scalable process flow.

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  • Inkjet Printed Single-Walled Carbon Nanotube Based Ambipolar and Unipolar Transistors for High-Performance Complementary Logic Circuits

    Advanced Electronic Materials (2016)

    Sadir Gabriele Bucella, Jorge Mario Salazar-Rios, Vladimir Derenskyi, Martin Fritsch, Ullrich Scherf, Maria Antonietta Loi, and Mario Caironi

    Inkjet printed single walled carbon nanotubes (SWCNT) field-effect transistors with mobilities of 15 and 7 cm2 V−1 s−1for holes and electrons, respectively, and high on–off ratio, are demonstrated. The high loading of the ink formulation and high electronic quality of the sorted SWCNT enable facile printing of networks displaying high coverage and effective mobility already after a single printing pass. Balanced ambipolarity or mainly unipolar behavior can be tuned by simply varying the number of printing passes, thus enabling the realization of high-performance complementary-like logic gates.

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  • Macroscopic and high-throughput printing of aligned nanostructured polymer semiconductors for MHz large-area electronics

    Nature Communications (2015)

    Sadir G. Bucella, Alessandro Luzio, Eliot Gann, Lars Thomsen, Christopher R. McNeill, Giuseppina Pace, Andrea Perinot, Zhihua Chen, Antonio Facchetti and Mario Caironi

    High-mobility semiconducting polymers offer the opportunity to develop flexible and large-area electronics for several applications, including wearable, portable and distributed sensors, monitoring and actuating devices. An enabler of this technology is a scalable printing process achieving uniform electrical performances over large area. As opposed to the deposition of highly crystalline films, orientational alignment of polymer chains, albeit commonly achieved by non-scalable/slow bulk alignment schemes, is a more robust approach towards large-area electronics. By combining pre-aggregating solvents for formulating the semiconductor and by adopting a room temperature wired bar-coating technique, here we demonstrate the fast deposition of submonolayers and nanostructured films of a model electron-transporting polymer. Our approach enables directional self-assembling of polymer chains exhibiting large transport anisotropy and a mobility up to 6.4 cm2 V−1 s−1, allowing very simple device architectures to operate at 3.3 MHz. Thus, the proposed deposition strategy is exceptionally promising for mass manufacturing of high-performance polymer circuits.

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  • Injection Length in Staggered Organic Thin Film Transistors: Assessment and Implications for Device Downscaling

    Advanced Electronic Materials (2016)

    Dario Natali, Jiaren Chen, Francesco Maddalena, Francisco García Ferré, Fabio Di Fonzo and Mario Caironi

    In staggered thin film transistors, the injection length is the fraction of the gate to contact overlap that is effectively involved in current injection. Its assessment is important to properly downscale device dimensions. In fact, in order to increase transistor operation speed, the whole device footprint should be downscaled, which means both the gate to contact overlap and the channel length, as they affect the relative weight of gate to contact parasitic capacitances and the carrier transit time along the channel respectively. Nevertheless, it is not advisable to make the gate to contact overlap smaller than the injection length, because this negatively affects contact resist- ances. Suitable figures of merits are introduced to quantify these aspects, and a method is proposed to extract the injection length from electrical measurements. As an example of application, transistors based on the prototypical n-type polymer poly{[N,N′-bis(2-octyldodecyl)-naphthalene- 1,4,5,8-bis(dicarboximide)-2,6-diyl]-alt-5,5′-(2,2′-bithiophene)} (P(NDI2OD- T2) are analyzed. When the channel length is scaled while driving voltages are kept constant, in P(NDI2OD-T2) the injection length decreases as well, thus proving that the downscaling of the whole device footprint is feasible. The physical origins of this finding are analyzed and traced back to material properties, in order to suggest general guidelines for a successful transistor downscaling.

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  • High-Mobility Naphthalene Diimide and Selenophene-Vinylene-Selenophene-Based Conjugated Polymer: n-Channel Organic Field-Effect Transistors and Structure–Property Relationship

    Advanced Functional Materials (2016)

    Min Jae Sung, Alessandro Luzio, Won-Tae Park, Ran Kim, Eliot Gann,Francesco Maddalena, Giuseppina Pace, Yong Xu, Dario Natali, Carlo de Falco, Long Dang, Christopher R. McNeill, Mario Caironi, Yong-Young Noh, and Yun-Hi Kim

    Interdependence of chemical structure, thin-film morphology, and transport properties is a key, yet often elusive aspect characterizing the design and development of high-mobility, solution-processed polymers for large-area and flexible electronics applications. There is a specific need to achieve >1 cm2 V−1 s−1 field-effect mobilities (μ) at low processing temperatures in combination with environmental stability, especially in the case of electron-transporting polymers, which are still lagging behind hole transporting materials. Here, the synthesis of a naphthalene-diimide based donor–acceptor copolymer characterized by a selenophene vinylene selenophene donor moiety is reported. Optimized field-effect transistors show maximum μ of 2.4 cm2 V−1 s−1 and promising ambient stability. A very marked film structural evolution is revealed with increasing annealing temperature, with evidence of a remarkable 3D crystallinity above 180 °C. Conversely, transport properties are found to be substantially optimized at 150 °C, with limited gain at higher temperature. This discrepancy is rationalized by the presence of a surface-segregated prevalently edge-on packed polymer phase, dominating the device accumulated channel. This study therefore serves the purpose of presenting a promising, high-electron-mobility copolymer that is processable at relatively low temperatures, and of clearly highlighting the necessity of specifically investigating channel morphology in assessing the structure–property nexus in semiconducting polymer thin films.

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  • Ambipolar charge distribution in donor–acceptor polymer field-effect transistors
  • Direct-written polymer field-effect transistors operating at 20 MHz
  • Inkjet Printed Single-Walled Carbon Nanotube Based Ambipolar and Unipolar Transistors for High-Performance Complementary Logic Circuits
  • Macroscopic and high-throughput printing of aligned nanostructured polymer semiconductors for MHz large-area electronics
  • Injection Length in Staggered Organic Thin Film Transistors:  Assessment and Implications for Device Downscaling
  • High-Mobility Naphthalene Diimide and Selenophene-Vinylene-Selenophene-Based Conjugated Polymer: n-Channel Organic Field-Effect Transistors and Structure–Property Relationship

 

Full publications list with HEROIC contribution

 

Highly Planarized Naphthalene Diimide–Bifuran Copolymers with Unexpected Charge Transport Performance

R. Matsidik, A. Luzio, Ö. Askin, D. Fazzi, A. Sepe, U. Steiner, H. Komber, M. Caironi, and M. Sommer
Chemistry of Materials,29 (13),5473–5483 1−10, 2017

Water-Gated n‑Type Organic Field-Effect Transistors for Complementary Integrated Circuits Operating in an Aqueous Environment

R. Porrazzo, A. Luzio, S. Bellani, G. E. Bonacchini, Y.-Y. Noh, Y.-H. Kim, G. Lanzani, M. R. Antognazza, M. Caironi
ACS Omega 2, 1−10, 2017

On the Effect of Prevalent Carbazole Homocoupling Defects on the Photovoltaic Performance of PCDTBT:PC71BM Solar Cells

F. Lombeck, H. Komber, D. Fazzi, D. Nava, J. Kuhlmann, D. Stegerer, K. Strassel, J. Brandt, A. Diaz de Zerio Mendaza, C.Müller, W. Thiel, M. Caironi, R. Friend, and M. Sommer*
Adv. Energy Mater. 6, 1601232 2016
  

Self-aligned organic field-effect transistors on plastic with picofarad overlap capacitances and megahertz operating frequencies

S. G. Higgins, B. V. O. Muir, G. Dell'Erba, A. Perinot, M. Caironi, and A. J. Campbell
Appl. Phys. Lett. 108, 023302, 2016
 

Complementary Organic Logic Gates on Plastic Formed by Self-Aligned Transistors with Gravure and Inkjet Printed Dielectric and Semiconductors

Stuart G. Higgins, Beinn V. O. Muir, Giorgio Dell'Erba, Andrea Perinot, Mario Caironi andAlasdair J. Campbell
Adv. Electron. Mater., 2, 2, 2016
DOI: 10.1002/aelm.201500272

 

Two-dimensional charge transport in molecularly ordered polymer field-effect transistors

V. D’Innocenzo, A. Luzio, H. Abdalla, S. Fabiano, M. A. Loi, D. Natali, A. Petrozza, M. Kemerink, M. Caironi
Journal of Materials Chemistry C, 4, 11135-11142, 2016
 

Effects of PNDIT2 end groups on aggregation, thin film structure, alignment and electron transport in field-effect transistors

R. Matsidik, A. Luzio, S. Hameury, H. Komber, C. R. McNeill, M. Caironi, M. Sommer
Journal of Materials Chemistry C, 4, 10371-10380, 2016
 

High-Performance Organic Field-Effect Transistors with Directionally Aligned Conjugated Polymer Film Deposited from Pre-Aggregated Solution

Nam-Koo Kim, Soo-Young Jang, Giuseppina Pace, Mario Caironi, Won-Tae Park, Dongyoon Khim, Juhwan Kim, Dong-Yu Kim and Yong-Young Noh
Chem. Mater., 27 (24), pp 8345–8353, 2015

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