E. van Veenendaal

A 13.56-MHz RFID System Based on Organic Transponders

RFID tags based on organic transistors are described, discussing in detail the IC blocks used to build the logic and the radio. Tags energized and read out at 13.56 MHz, de facto standard frequency for item-level identification, have been tested and enabled for the first time multiple-object identification, using different 6-bit codes. A complete 64-bit transponder, the most complex organic RFID tag reported to date, operates at 125 kHz and employs 1938 transistors

Dopant density determination in disordered organic field-effect transistors

We demonstrate that, by using a concentric device geometry, the dopant density and the bulk charge-carrier mobility can simultaneously be estimated from the transfer characteristics of a single disordered organic transistor. The technique has been applied to determine the relation between the mobility and the charge density in solution-processed poly(2,5-thienylene vinylene) and poly(3-hexyl thiophene) thin-film field-effect transistors. The observation that doping due to air exposure takes place already in the dark, demonstrates that photoinduced oxygen doping is not the complete picture.

Switch-on voltage in disordered organic field-effect transistors

The switch-on voltage for disordered organic field-effect transistors is defined as the flatband voltage, and is used as a characterization parameter. The transfer characteristics of the solution processed organic semiconductors pentacene, poly(2,5-thienylene vinylene) and poly(3-hexyl thiophene) are modeled as a function of temperature and gate voltage with a hopping model in an exponential density of states. The data can be described with reasonable values for the switch-on voltage, which is independent of temperature. This result also demonstrates that the large threshold voltage shifts as a function of temperature reported in the literature constitute a fit parameter without a clear physical basis.

Scaling behavior and parasitic series resistance in disordered organic field-effect transistors

The scaling behavior of the transfer characteristics of solution-processed disordered organic thin-film transistors with channel length is investigated. This is done for a variety of organic semiconductors in combination with gold injecting electrodes. From the channel-length dependence of the transistor resistance in the conducting ON-state, we determine the field-effect mobility and the parasitic series resistance. The extracted parasitic resistance, typically in the MΩ range, depends on the applied gate voltage, and we find experimentally that the parasitic resistance decreases with increasing field-effect mobility.

An 8-Bit, 40-Instructions-Per-Second Organic Microprocessor on Plastic Foil

Forty years after the first silicon microprocessors, we demonstrate an 8-bit microprocessor made from plastic electronic technology directly on flexible plastic foil. The operation speed is today limited to 40 instructions per second. The power consumption is as low as 100 μW. The ALU-foil operates at a supply voltage of 10 V and back-gate voltage of 50 V. The microprocessor can execute user-defined programs: we demonstrate the execution of the multiplication of two 4-bit numbers and the calculation of the moving average of a string of incoming 6-bit numbers. To execute such dedicated tasks on the microprocessor, we create small plastic circuits that generate the sequences of appropriate instructions. The near transparency, mechanical flexibility, and low power consumption of the processor are attractive features for integration on everyday objects, where it could be programmed as, amongst other items, a calculator, timer, or game controller.

A Fully Integrated

In this work we present a fully integrated first order continuous-time ΔΣ ADC made in a pentacene-based dual-gate organic thin-film transistor technology on flexible plastic foil. The ADC achieves a precision of 26.5 dB at a clock speed of 500 Hz and draws 100 μA from a 15 V power supply. As sub-blocks of the ADC, we also present a Vt -insensitive single-stage differential amplifier with 10 kHz GBW, a 3-stage operational amplifier, an integrator, a comparator and a level shifter. The circuits are designed following a strict Vt -insensitive design strategy and use high-pass filters for offset cancellation. The active area is 13 × 20 mm2.

\Delta \Sigma

A dual-gate organic thin-film transistor is realized using solution-processed organic semiconductor and insulator layers. Electrodes are made from gold. Compared to conventional single-gate transistors, this device type has a higher on current and steeper subthreshold slope. We show that the improved performance is the result of a nonconstant threshold voltage rather than formation of a second accumulation channel. Formation of a second accumulation channel does occur but the field-effect mobility associated with this channel is a factor 104 lower than the primary channel due to the relatively rough insulator-semiconductor interface.

ADC in Organic Thin-Film Transistor Technology on Flexible Plastic Foil

In this work a technology to fabricate low-voltage amorphous gallium-indium-zinc oxide thin film transistors (TFTs) based integrated circuits on 25 µm foils is presented. High performance TFTs were fabricated at low processing temperatures (<150 °C) with field effect mobility around 17 cm2 /V s. The technology is demonstrated with circuit building blocks relevant for radio frequency identification applications such as high-frequency functional code generators and efficient rectifiers. The integration level is about 300 transistors.

Dual-gate organic thin-film transistors

Rollable electrophoretic displays with an active-matrix backplane are an emerging application of organic electronics. Integrating row shift registers on the display backplane reduces the number of interconnects and the footprint. Stand-alone shift registers using organic electronics on a flexible substrate are designed, realized, and characterized. The circuit contains 240 stages and has over 4000 transistors. Furthermore, a 240-stage shift register is integrated with a QVGA active-matrix display.

Low-voltage gallium–indium–zinc–oxide thin film transistors based logic circuits on thin plastic foil: Building blocks for radio frequency identification application

In this work, we present the implementation and measurement results of all analog building blocks of an organic smart sensor system on foil. The presented building blocks are a 1D and a 2D 4 × 4 pixel flexible capacitive touch sensor with a sample rate of 1.5 kS/s, a DC-connected two-stage opamp with a 20 dB DC gain, a Dickson DC-DC up-converter with output bias voltages up to 60 V and down to - 40 V which are used as a bias voltage in the other building blocks, and a ΔΣ ADC with a 26.5 dB precision and a band width of 15.6 Hz. The sensors, the opamp, the DC-DC converter and the ADC respectively consume 6 μA, 15 μA, 1 μA and 100 μA from a 15 V power supply.