Gerwin Gelinck

Solution-processed small molecule transistors with low operating voltages and high grain-boundary anisotropy

We present a new soluble pentacene derivative with ethyl substitutions in the 1,13,14,22 backbone positions to modulate the solubility and film forming properties of this material compared to triisopropylsilylethynyl (TIPS) pentacene. This permits reproducible production of molecularly highly ordered structures that feature average transistor mobilities in excess of 1 cm2 V−1 s−1 depending on crystal orientation by careful selection of casting conditions.

Balancing Hole and Electron Conduction in Ambipolar Split-Gate Thin-Film Transistors

Complementary organic electronics is a key enabling technology for the development of new applications including smart ubiquitous sensors, wearable electronics, and healthcare devices. High-performance, high-functionality and reliable complementary circuits require n- and p-type thin-film transistors with balanced characteristics. Recent advancements in ambipolar organic transistors in terms of semiconductor and device engineering demonstrate the great potential of this route but, unfortunately, the actual development of ambipolar organic complementary electronics is currently hampered by the uneven electron (n-type) and hole (p-type) conduction in ambipolar organic transistors. Here we show ambipolar organic thin-film transistors with balanced n-type and p-type operation. By manipulating air exposure and vacuum annealing conditions, we show that well-balanced electron and hole transport properties can be easily obtained. The method is used to control hole and electron conductions in split-gate transistors based on a solution-processed donor-acceptor semiconducting polymer. Complementary logic inverters with balanced charging and discharging characteristics are demonstrated. These findings may open up new opportunities for the rational design of complementary electronics based on ambipolar organic transistors.

Dielectric interface-dependent spatial charge distribution in ambipolar polymer semiconductors embedded in dual-gate field-effect transistors

The spatial charge distribution in diketopyrrolopyrrole-containing ambipolar polymeric semiconductors embedded in dual-gate field-effect transistors (DGFETs) was investigated. The DGFETs have identical active channel layers but two different channel/gate interfaces, with a CYTOP™ organic dielectric layer for the top-gate and an octadecyltrichlorosilane (ODTS) self-assembled monolayer-treated inorganic SiO2 dielectric for the bottom-gate, respectively. Temperature-dependent transfer measurements of the DGFETs were conducted to examine the charge transport at each interface. By fitting the temperature-dependent measurement results to the modified Vissenberg–Matters model, it can be inferred that the top-channel interfacing with the fluorinated organic dielectric layers has confined charge transport to two-dimensions, whereas the bottom-channel interfacing with the ODTS-treated SiO2 dielectric layers has three-dimensional charge transport.

Flexible metal-oxide thin film transistor circuits for RFID and health patches

We discuss in this paper the present state and future perspectives of thin-film oxide transistors for flexible electronics. The application case that we focus on is a flexible health patch containing an analog sensor interface as well as digital electronics to transmit the acquired data wirelessly to a base station. We examine the electronic performance of amorphous Indium-Gallium-Zinc-Oxide (a-IGZO) during mechanical bending. We discuss several ways to further boost the electronic transistor performance of n-type amorphous oxide semiconductors, by modifying the semiconductor or by improving the transistor architecture. We show analog and digital circuits constructed with several architectures, all based on n-type-only amorphous oxide technology. From circuit point of view, the discovery of a p-type amorphous semiconductor matching known n-type amorphous semiconductors would be of great importance. The present best-suited p-type is SnO, but it is poly-crystalline in nature and shows some ambipolarity due to the presence of n-type SnO2. In search of a better p-type semiconductor, preferably amorphous, we present recent insights into the band structure of potential amorphous oxide p-type semiconductors.

High performance x-ray imaging detectors on foil using solution-processed organic photodiodes with extremely low dark leakage current (Presentation Recording)

High performance X-ray imaging detectors on foil using solution-processed organic photodiodes with extremely low dark leakage current Abhishek Kumara, Date Moeta, Albert van Breemena, Santhosh Shanmugama, Jan-Laurens van der Steena, Jan Gilota, Ronn Andriessena, Matthias Simonb, Walter Ruettenb, Alexander U. Douglasb, Rob Raaijmakersc, Pawel E. Malinowskid, Kris Mynyd and Gerwin H. Gelincka,e a. Holst Centre/TNO, High Tech Campus 31, Eindhoven 5656 AE, The Netherlands b. Philips Research, High Tech Campus 34, 5656 AE Eindhoven, The Netherlands c. Philips Healthcare, Veenpluis 6-8, 5684 PC Best, The Netherlands d. Department of Large Area Electronics, imec vzw, Kapeldreef 75, Leuven B3001, Belgium e. Applied Physics Department, TU Eindhoven, Eindhoven, The Netherlands We demonstrate high performance X-ray imaging detectors on foil suitable for medical grade X-ray imaging applications. The detectors are based on solution-processed organic photodiodes forming bulk-heterojunctions from photovoltaic donor and acceptor blend. The organic photodiodes are deposited using an industrially compatible slot die coating technique with end of line processing temperature below 100°C. These photodiodes have extremely low dark leakage current density of 10-7 mA/cm2 at -2V bias with very high yield and have peak absorption around 550 nm wavelength. We combine these organic photodiodes with high mobility metal oxide semiconductor based thin film transistor arrays with high pixel resolution of 200ppi on thin plastic substrate. When combined with a typical CsI(TI) scintillator material on top, they are well suited for low dose X-ray imaging applications. The optical crosstalk is insignificant upto resolution of 200 ppi despite the fact that the photodiode layer is one continuous layer and is non-pixelated. Low processing temperatures are another key advantage since they can be fabricated on plastic substrate. This implies that we can make X-ray detectors on flexible foil. Those detectors can be mechanically more robust and light weight when compared to amorphous Si based detectors fabricated on glass substrate.