Design, synthesis, and photophysical studies of substituted indigo derivatives for p-type organic thin film transistors

Comparison of electrical characteristics for p-type and n-type organic thin film transistors using copper phthalocyanine

High performance printed N and P-type OTFTs enabling digital and analog complementary circuits on flexible plastic substrate

Characterization and modeling of organic thin-film transistors based π-conjugated small molecule tetraphenyldibenzoperiflanthene: Effects of channel length

This paper presents a printed organic complementary technology on flexible plastic substrate with high performance N and P-type Organic Thin Film Transistors (OTFTs), based on small-molecule organic semiconductors in solution. Challenges related to the integration of both OTFT types in a common complementary flow are addressed, showing the importance of surface treatments. Data on single devices and elementary complementary digital circuits (inverters and ring oscillators) are presented, demonstrating that a robust and reliable flow with high electrical performances can be established for printed organic devices.

In this paper, we have study two types of thin-film organic transistors and their application to release the organic inverter. For manufacturing p-type and n-type organic thin film transistors (OTFT), pentacene and N,N'-ditridecylperylene-3,4,9,10-tetracarboxylic diimide (PTCDI-C13H27) have been used as organic semiconductors active layers. These organic thin film transistors have been shown excellent ambipolar operation. We proceeded initially to model and study these complementary organic transistors individually. Therefore we present the various electrical parameters resulting from the modeling of these two types of organic transistors (n-type and p-type) as well as the various parameters characterizing the organic inverter. Very good agreement is obtained between the experimental electrical characteristics of the two types of organic transistors and the characteristics obtained by the analytical model, as well as the experimental characteristics of the organic inverter thus produced.

Fluorene−thiophene oligomers show great promise as the active material in p-type organic thin film transistors (TFTs) because of their good performance and good stability under ambient conditions. In this study, a series of fluorene−thiophene co-oligomers were asymmetrically substituted with an alkyl group to probe the effect chemical structure has on their thin film properties. The alkyl groups are n-hexyl, n-octyl, and n-dodecyl, respectively. These oligomers were characterized by elemental analysis, mass spectrometry, differential scanning calorimetry, and thermogravimetric analysis, whereas the thin films of these oligomers were characterized by X-ray diffraction, atomic force microscopy, and field-effect transistor measurements. We found that the performance of these asymmetric molecules is similar to their symmetric counterparts. Mobilities as high as 0.16 cm2 V-1 s-1 were found for the n-dodecyl-substituted oligomer.

Synthesis and properties of phenothiazylene vinylene and bithiophene-based copolymers for organic thin film transistors

Bias stress instability has been investigated in printed p-channel organic thin film transistors. The observed instability is related to two mechanisms: one, dominating at low T and causing “mobile ions” like threshold voltage variations is probably due to creation/annihilation of acceptor-like states; the second one, causing charge-trapping like instability, dominates at high T. High drain voltage bias stress experiments, inducing device self-heating, present threshold voltage variations, suggest a channel temperature rise ranging from 50 to 60 °C. The results point out the role of self-heating on the bias-stress instability, which is related to a combination of bias and temperature conditions.

We demonstrate an organic smart label electronic system using p-type organic thin film transistors (OTFT) for temperature sensing applications. The electronic label consists of all organic temperature sensor, memory, logic and interface circuits and detects whether the critical temperature threshold value has been exceeded and records the data digitally in write-once-read-many (WORM) form that can be transmitted to a reader through wireless communication. A comparator is used to interface the sensor to the logic part. The logic circuit block processes and bundles the sensor information along with the necessary additional information that is required for a successful wireless transmission. We have demonstrated the operation of the reported organic smart label system using a silicon based modulator/rectifier circuit for RF communication. The organic logic circuit was built using standard cell design approach with approximately 180 p-type OTFTs. All the circuits were operated with a V <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">DD</sub> of -20 V.

Thin film transistors (TFT) have been gaining special attention from researchers in recent years because they are seen as an alternative to traditional MOSFET for future electronic device development. In this manuscript, the performance characteristics of n-channel Indium-Galium-Zinc-Oxide (IGZO) Top Gate Top Contact (TGTC) Thin Film Transistors (TFTs) for various insulating materials including Al2O3, Ta2O5, HfO2, Si3N4, SiO2, and Y2O3 are investigated and compared. This is followed by a comparison of p-type pentacene-based TGTC Organic Thin Film Transistors (OTFT). During simulation tests, the Silvaco Atlas tool is employed, and the I-V characteristic curve is analyzed to discover the important parameters. The proposed TFT's competency is demonstrated by extensive simulation results that contrast it with other models of a similar nature concerning threshold voltage, current ratio, subthreshold slope, mobility and Figure of Merit (FoM). The results demonstrate a trade-off between mobility and current ratio concerning the permittivity of the dielectric layer, with tantalum oxide (Ta2O5) providing the best outcomes in terms of FoM. According to simulation testing, the tantalum pentoxide (Ta2O5) gate insulating layer based on IGZO surpasses its rivals including the p-channel pentacene-based OTFT by offering mobility of 1.47 cm2V-1s-1, a current ratio of 1.36×106 and FoM of 198.87.

A new acceptor-donor-acceptor (A-D-A) small molecule based on benzodithiophene (BDT) and diketopyrrolopyrrole (DPP) is synthesized via a Stille cross-coupling reaction. A highly conjugated selenophene-based side group is incorporated into each BDT unit to generate a 2D soluble small molecule (SeBDT-DPP). SeBDT-DPP thin films produce two distinct absorption peaks. The shorter wavelength absorption (400 nm) is attributed to the BDT units containing conjugated selenophene-based side groups, and the longer wavelength band is due to the intramolecular charge transfer between the BDT donor and the DPP acceptor. SeBDT-DPP thin films can harvest a broad solar spectrum covering the range 350-750 nm and have a low bandgap energy of 1.63 eV. Solution-processed field-effect transistors fabricated with this small molecule exhibit p-type organic thin film transistor characteristics, and the field-effect mobility of a SeBDT-DPP device is measured to be 2.3 × 10-3 cm2 V-1 s-1 . A small molecule solar cell device is prepared by using SeBDT-DPP as the active layer is found to exhibit a power conversion efficiency of 5.04% under AM 1.5 G (100 mW cm-2 ) conditions.

Synthesis and characterization of diselenenoquinoxaline-based donor–acceptor polymers for organic photovoltaic cells

Synthesis and characterization of a pentaselenophene-based donor–acceptor copolymer for use in organic photovoltaic cells

Mechanical flexibility and compatibility of printing processes are key advantage that organic electronic devices have over conventional inorganic devices. However, one of the major remaining issues for organic devices is insufficient mechanical durability of printed electrodes. Here we have investigated the mechanical durability of both p-type and n-type organic thin-film transistors (TFTs) with ink-jet printed silver electrodes from silver nanoparticle inks. The modified silver nanoparticle inks enabled the strong adhesion to the underlying polymer layer, and the fabricated organic TFTs exhibited excellent reproducibility in the bending cycle tests. The strong channel length dependence on the strain sensitivity was observed in both p-type and n-type organic TFTs. The organic TFTs with a short-channel exhibited higher sensitivity to the bending strain. These results suggest that the flexible organic TFTs with printed silver electrodes have excellent mechanical durability and are useful for bending and strain sensors.

Ultrathin electronic circuits that can be manufactured by using conventional printing technologies are key elements necessary to realize wearable health sensors and next-generation flexible electronic devices. Due to their low level of power consumption, complementary (CMOS) circuits using both types of semiconductors can be easily employed in wireless devices. Here, we describe ultrathin CMOS logic circuits, for which not only the source/drain electrodes but also the semiconductor layers were printed. Both p-type and n-type organic thin film transistor devices were employed in a D-flip flop circuit in the newly developed stacked structure and exhibited excellent electrical characteristics, including good carrier mobilities of 0.34 and 0.21 cm2 V−1 sec−1, and threshold voltages of nearly 0 V with low operating voltages. These printed organic CMOS D-flip flop circuits exhibit operating frequencies of 75 Hz and demonstrate great potential for flexible and printed electronics technology, particularly for wearable sensor applications with wireless connectivity.