Chapter Interlayer Processing in Active Matrix OLED Displays

Medical genetic

Reconfigurable Complementary Logic Circuits with Ambipolar Organic Transistors

Ambipolar organic electronics offer great potential for simple and low-cost fabrication of complementary logic circuits on large-area and mechanically flexible substrates. Ambipolar transistors are ideal candidates for the simple and low-cost development of complementary logic circuits since they can operate as n-type and p-type transistors. Nevertheless, the experimental demonstration of ambipolar organic complementary circuits is limited to inverters. The control of the transistor polarity is crucial for proper circuit operation. Novel gating techniques enable to control the transistor polarity but result in dramatically reduced performances. Here we show high-performance non-planar ambipolar organic transistors with electrical control of the polarity and orders of magnitude higher performances with respect to state-of-art split-gate ambipolar transistors. Electrically reconfigurable complementary logic gates based on ambipolar organic transistors are experimentally demonstrated, thus opening up new opportunities for ambipolar organic complementary electronics.115Ysciescopu

Interlayer Processing in Active Matrix OLED Displays

Medical genetic

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. ? 2017 The Author(s).114Ysciescopu

Correlated theory of triplet photoinduced absorption in phenylene-vinylene chains

In this paper we present results of large-scale correlated calculations of triplet photoinduced absorption (PA) spectrum of oligomers of poly-(para)phenylenevinylene (PPV) containing up to five phenyl rings. In particular, the high-energy features in the triplet PA spectrum of oligo-PPVs are the focus of this study, which, so far, have not been investigated theoretically, or experimentally. The calculations were performed using the Pariser-Parr-Pople (PPP) model Hamiltonian, and many-body effects were taken into account by means of multi-reference singles-doubles configuration interaction procedure (MRSDCI), without neglecting any molecular orbitals. The computed triplet PA spectrum of oligo-PPVs exhibits rich structure consisting of alternating peaks of high and low intensities. The predicted higher energy features of the triplet spectrum can be tested in future experiments. Additionally, theoretical estimates of exciton binding energy are also presented.Comment: To appear in Phys. Rev.

Excitons and polarons in Luminescent conjugated polymers. A flash-photolysis and pulse-radiolysis study

Applied Science

Charge Recombination Via Long-Distance Electron Transfer through Frozen and Molten N-Alkyl Chains in Pulse-Irradiated Mesomorphic Phthalocyanines

Contains fulltext : 28151___.PDF (publisher's version ) (Open Access

Space charge limitation on the response time of organic photodiodes

The dynamic response of an organic bulk heterojunction photodiode to small changes in applied bias or light intensity is investigated as function of the intensity of a constant background illumination by means of photoimpedance and transient photocurrent measurements. For bias voltages close to the open circuit voltage we find that the response timescale with the square root of the light intensity. The results can be quantitatively explained in terms of a space charge limitation on the photocurrent as predicted by Goodman and Rose (J. Appl. Phys. 42, 2823 (1971)). The relaxation time of the diode at open circuit corresponds to the lifetime of the slowest charge carrier in the diode. This relaxation time is determined by the dielectric constant and the smallest of the two carrier mobilities in the bulk heterojunction. This illustrates the importance of balanced carrier mobilities for obtaining diodes with fast response time at low bias for e.g. imaging arrays

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

Liquid phase demixing in ferroelectric/semiconducting polymer blends: an experimental and theoretical study

This article describes a combined experimental and theoretical study on nanophase structure development as a result of liquid phase demixing in solution-cast blends of the organic semiconductor poly(9,9'-dioctyl fluorene) (PFO) and the ferroelectric polymer poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)). Blend layers (200 nm) are prepared by spin coating a 1:9 (w/w) PFO:P(VDF-TrFE) blend solution in a common solvent on a poly(ethylenedioxy thiophene)/poly(styrene sulfonate) substrate. Owing to the pronounced incompatibility between the two polymers, a strong phase-separated morphology is obtained, characterized by disk-like nanodomains of PFO embedded in a P(VDF-TrFE) matrix, as revealed by scanning electron microscopy. By varying the processing conditions, we find the average domain size and standard deviation to increase with spinning time. The considerable increase in domain size suggests the coarsening process not to be impeded by a steep rise in viscosity. This indicates solvent evaporation to be only moderate within the experimental time frame. The evolution of the observed phase morphology is modeled using ternary diffuse interface theory integrated with a modified Flory-Huggins (FH) treatment of the homogeneous (bulk) free energy of mixing, to account for significant molecular differences between the active blend components. Using calculated FH interaction parameters, the model confirms the phase separation to occur via spinodal decomposition of the blend solution during spin coating, as suggested by experimental observations. The simulated phase morphologies as well as the modeled trends in domain growth and standard deviation compare favorably with the experimental data. © 2011 Wiley Periodicals, Inc