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The interest for biodegradable electronic devices is rapidly increasing for application in the field of wearable electronics, precision agriculture, biomedicine, and environmental monitoring. Energy storage devices integrated on polymeric substrates are of particular interest to enable the large-scale on field use of complex devices. This work presents a novel class of eco-friendly supercapacitors based on biodegradable poly(3-hydroxybutyrrate) PHB, ionic liquids, and cluster-assembled gold electrodes. By electrochemical characterization, we demonstrate the possibility of tuning the supercapacitor energetic performance according to the type and amount of the ionic liquid employed. Our devices based on hydrophobic plastic materials are stable under cyclic operation and resistant to moisture exposure.

This study shows a correlation relationship between the QRS integral and the ST-segment deviation.We show significant differences between AC- and DC-coupled ECG recorded signals.As the work is based on clinical digital ECG records stored in raw format, there is an impact for clinicians as well as technicians.However, we also show that in a clinical content, the alterations to the P wave and QRS complex are minor. Background and objectiveThe first-order high-pass filter (AC coupling) has previously been shown to affect the ECG for higher cut-off frequencies. We seek to find a systematic deviation in computer measurements of the electrocardiogram when the AC coupling with a 0.05Hz first-order high-pass filter is used. MethodsThe standard 12-lead electrocardiogram from 1248 patients and the automated measurements of their DC and AC coupled version were used. We expect a large unipolar QRS-complex to produce a deviation in the opposite direction in the ST-segment. ResultsWe found a strong correlation between the QRS integral and the offset throughout the ST-segment. The coefficient for J amplitude deviation was found to be 0.277V/(Vs). ConclusionsPotential dangerous alterations to the diagnostically important ST-segment were found. Medical professionals and software developers for electrocardiogram interpretation programs should be aware of such high-pass filter effects since they could be misinterpreted as pathophysiology or some pathophysiology could be masked by these effects.

The organic light-emitting transistors (OLETs) with a novel tri-layer organic semiconducting heterostructure architecture and good performance, including record high EQE, is presented. In addition, an active-matrix display based on OLETs, without driving TFTs, will be demonstrated on a plastic substrate. The potential advantages of such technologies will be discussed.

Background: \ud Automated measurements of electrocardiographic (ECG) intervals by current-generation digital electrocardiographs are critical to computer-based ECG diagnostic statements, to serial comparison of ECGs, and to epidemiological studies of ECG findings in populations. A previous study demonstrated generally small but often significant systematic differences among 4 algorithms widely used for automated ECG in the United States and that measurement differences could be related to the degree of abnormality of the underlying tracing. Since that publication, some algorithms have been adjusted, whereas other large manufacturers of automated ECGs have asked to participate in an extension of this comparison.\ud \ud Methods: \ud Seven widely used automated algorithms for computer-based interpretation participated in this blinded study of 800 digitized ECGs provided by the Cardiac Safety Research Consortium. All tracings were different from the study of 4 algorithms reported in 2014, and the selected population was heavily weighted toward groups with known effects on the QT interval: included were 200 normal subjects, 200 normal subjects receiving moxifloxacin as part of an active control arm of thorough QT studies, 200 subjects with genetically proved long QT syndrome type 1 (LQT1), and 200 subjects with genetically proved long QT syndrome Type 2 (LQT2).\ud \ud Results: \ud For the entire population of 800 subjects, pairwise differences between algorithms for each mean interval value were clinically small, even where statistically significant, ranging from 0.2 to 3.6 milliseconds for the PR interval, 0.1 to 8.1 milliseconds for QRS duration, and 0.1 to 9.3 milliseconds for QT interval. The mean value of all paired differences among algorithms was higher in the long QT groups than in normals for both QRS duration and QT intervals. Differences in mean QRS duration ranged from 0.2 to 13.3 milliseconds in the LQT1 subjects and from 0.2 to 11.0 milliseconds in the LQT2 subjects. Differences in measured QT duration (not corrected for heart rate) ranged from 0.2 to 10.5 milliseconds in the LQT1 subjects and from 0.9 to 12.8 milliseconds in the LQT2 subjects.\ud \ud Conclusions: \ud Among current-generation computer-based electrocardiographs, clinically small but statistically significant differences exist between ECG interval measurements by individual algorithms. Measurement differences between algorithms for QRS duration and for QT interval are larger in long QT interval subjects than in normal subjects. Comparisons of population study norms should be aware of small systematic differences in interval measurements due to different algorithm methodologies, within-individual interval measurement comparisons should use comparable methods, and further attempts to harmonize interval measurement methodologies are warranted.

Self-Assembled Monolayers (SAMs) on gold were successfully implemented to passivate gold contact organic cell stimulating and sensing transistors. The results show the devices to be greatly insulated from water. This breakthrough is proposed as a technological improvement for bio-stimulation and bio-sensing organic field-effect devices.

Organic light-emitting transistors (OLETs) are multifunctional optoelectronic devices that hold great promise for a variety of applications, including flat panel displays, integrated light sources for sensing and optical communication systems. The narrow illumination area within the device channel is considered intrinsic to the device architecture and is a severe technological drawback for all those applications where a controlled, wide and homogeneous emission area is required. Here it is shown that not only the position but also the extension of the emission area is voltage-tunable, and the entire channel of the transistor can be homogeneously illuminated. The modeling of the exciton distribution within the channel at the different bias conditions coupled to the modeling of the device emission profile highlights that excitons are spread through the entire channel width and across the bulk of the central emission layer of the p-channel/emitter/n-channel trilayer active heterostructure.

Real-time stimulation and recording of neural cell bioelectrical activity could provide an unprecedented insight in understanding the functions of the nervous system, and it is crucial for developing advanced in vitro drug screening approaches. Among organic materials, suitable candidates for cell interfacing can be found that combine long-term biocompatibility and mechanical flexibility. Here, we report on transparent organic cell stimulating and sensing transistors (O-CSTs), which provide bidirectional stimulation and recording of primary neurons. We demonstrate that the device enables depolarization and hyperpolarization of the primary neuron membrane potential. The transparency of the device also allows the optical imaging of the modulation of the neuron bioelectrical activity. The maximal amplitude-to-noise ratio of the extracellular recording achieved by the O-CST device exceeds that of a microelectrode array system on the same neuronal preparation by a factor of 16. Our organic cell stimulating and sensing device paves the way to a new generation of devices for stimulation, manipulation and recording of cell bioelectrical activity in vitro and in vivo.

Goal: The ST segment of an electrocardiogram (ECG) is very important for the correct diagnosis of an acute myocardial infarction. Most clinical ECGs are recorded using an ACcoupled ECG amplifier. It is well known, that first-order high-pass filters used for the AC coupling can affect the ST segment of an ECG. This effect is stronger the higher the filter's cut-off frequency is and the larger the QRS integral is. We present a formula that estimates these changes in the ST segment and therefore allows for correcting ST measurements that are based on an ACcoupled ECG. Methods: The presented correction formula can be applied when only four parameters are known: the possibly estimated QRS area A , the QRS duration W, the beat-to-beat interval $T_{{\rm{RR}}}$ , and the filter time constant T , further, the time point $T_{j}$ to correct—after the J point—must be specified. Results: The formula is correct within 0.6% until 40% ms after the J point and within 6% until 80 ms after the J point. Conclusion and significance: It is not necessary to have the raw data available and the formula therefore opens up the possibility of reevaluating studies that are based on ACcoupled ECGs and compare the results of such studies with studies that are based on newer, DC-coupled ECGs.

The relationships between the molecular structure, packing modalities, charge mobility and light emission in organic thin films is a highly debated and controversial issue, with both fundamental and technological implications in the field of organic optoelectronics. Thieno(bis)imide (TBI) based molecular semiconductors provide an interesting combination of good processability, tunable self-assembly, ambipolar charge transport and electroluminescence, and are therefore an ideal test base for fundamental studies on the structure-property correlation in multifunctional molecular systems. Herein, we introduce a new class of thieno(bis)imide quaterthiophenes having alkyl side chains of different shapes (linear, cyclic, branched) and lengths (C1-C8). We found that contrarily to what is generally observed in most molecular semiconductors, the length of the alkyl substituent does not affect the optical, self-assembly and charge transport properties of TBI materials. However, different electroluminescence powers are observed by increasing the alkyl side, this suggesting a potential tool for the selective modulation of TBI functionalities. A deep experimental and theoretical investigation on this new family of TBI materials is provided. This journal is © the Partner Organisations 2014.

We analyzed the effects of Electrostatic Discharge events on large area high voltage Organic Thin Film Transistors, using the transmission line pulsing technique. These transistors survived ESD events exceeding 500V. A partial dielectric breakdown occurred at voltage higher tan 600V. Small mobility and threshold voltage variations are observed, prior to breakdown.

The organic light-emitting transistors (OLETs) with a novel tri- layer organic semiconducting heterostructure architecture and good performance, including record high EQE, is presented. In addition, an active-matrix display based on OLETs, without driving TFTs, will be demonstrated on a plastic substrate. The potential advantages of such technologies will be discussed.

A new anthracene-based twisted oligomer combining a rigid anthracene-xylene core with diphenylamine ends 4,4'-(anthracene-9,10-diyl) bis(2,5-dimethyl-N, N-diphenylaniline), DiPAXA, is herein presented as an efficient and deep blue emitter material. By exploiting DiPAXA as an emissive layer and 2,7-dioctyl[1]benzothieno[3,2-b][1] benzothiophene (C8-BTBT) as a p-type semiconducting layer, we realize a blue emitting unipolar light emitting transistor (OLET) with a maximum external quantum efficiency (EQE) of 0.13%, a charge mobility up to 0.32 cm(2) V-1 s(-1) and CIE color coordinates of (0.18, 0.21), i.e. closer to currently available standards (PAL, NTSC). Moreover, comparison with other anthracene-based blue emitters highlights the suitability of this family of twisted anthracene-xylene compounds for unipolar blue OLET applications as a result of the enhanced performances in terms of CIE coordinates and light emission output of newly synthesized DiPAXA.

In this work, the fabrication, the electrical and optical characterization of red organic light emitting transistors using thin film made of alumina grown by atomic layer deposition (ALD) coupled with PMMA (poly(methyl-methacrylate)) as gate dielectric material are reported. Use of ALD-grown Al2O3 is shown to greatly reduce the operation range and the threshold voltage in this class of devices as compared to polymer-based dielectric counterpart, while at the same time comparable optical performances are maintained. Further, reducing the oxide layer thickness demonstrates the possibility of fine tuning the device working conditions, while maintaining optoelectronic performances, robustness and very low leakage current.

We report on a three-layer organic light-emitting transistor (3L-OLET) comprising a novel set of semiconductors as transport layers, 2,7-Dioctyl[1]benzothieno[3,2-b][1]benzothiophene (C8-BTBT) and 2,5-bis[4-(heptadecafluorooctyl)phenyl]thieno[3,2-b]thiophene (N-F2-6). These materials, combined with an emissive layer of a 4,4'-Bis(N-carbazolyl)-1,1'-biphenyl (CBP) derivative, 4,4'-bis(3,6-dineopentyl-9H-carbazole-9-yl)-1,'-biphenyl (NP4-CBP) and a new dye (BLUE1), have been used to obtain blue electroluminescent device.

Since the introduction of digital electrocardiographs, high-pass filters have been necessary for successful analog-to-digital conversion with a reasonable amplitude resolution. On the other hand, such high-pass filters may distort the diagnostically significant ST-segment of the ECG, which can result in a misleading diagnosis. We present an inverting filter that successfully undoes the effects of a 0.05 Hz single pole high-pass filter. The inverting filter has been tested on more than 1600 clinical ECGs with one-minute durations and produces a negligible mean RMS-error of 3.1*10(-8) LSB. Alternative, less strong inverting filters have also been tested, as have different applications of the filters with respect to rounding of the signals after filtering. A design scheme for the alternative inverting filters has been suggested, based on the maximum strength of the filter. With the use of the suggested filters, it is possible to recover the original DC-coupled ECGs from AC-coupled ECGs, at least when a 0.05 Hz first order digital single pole high-pass filter is used for the AC-coupling.

In this work we report the stimulation of astrocytic calcium signalling using an organic cell sensing and stimulating transistor (O-CST). We demonstrate that astroglial cells can adhere and proliferate on these devices giving us the possibility to stimulate bioelectrical activity in this type of cells. By the use of a microfluorimetric calcium imaging approach we show that our device is able to evoke an increase in intracellular calcium levels. This research opens a new path in the study of glial cells and their bioelectrical activity.

Organic molecular semiconductors are key components for a new generation of low cost, flexible, and large area electronic devices. In particular, ambipolar semiconductors endowed with electroluminescent properties have the potential to enable a photonic field-effect technology platform, whose key building blocks are the emerging organic light-emitting transistor (OLET) devices. To this aim, the design of innovative molecular configurations combining effective electrical and optical properties in the solid state is highly desirable. Here, we investigate the effect of the insertion of a thieno(bis)imide (TBI) moiety as end group in highly performing unipolar oligothiophene semiconductors on the packing, electrical, and optoelectronic properties of the resulting materials. We show that, regardless of the HOMO-LUMO energy, orbital distribution, and molecular packing pattern, a TBI end moiety switches unipolar and nonemissive oligothiophene semiconductors to ambipolar and electroluminescent materials. Remarkably, the newly developed materials enabled the fabrication of single layer molecular ambipolar OLETs with optical power comparable to that of the equivalent polymeric single layer devices.

In this work we report how to stimulate astrocytes calcium signalling using an organic cell sensing and stimulating transistor (O-CST). We demonstrate that astroglial cells can adhere and proliferate in these devices giving us the possibility to stimulate bioelectrical activity on this type of cells. By the use of calcium imaging we can prove that our device can cause an increase of intracellular calcium. This research opens a new path in the study of glial cells and their bioelectrical activity.

Despite their favorable electronic and structural properties, the synthetic development and incorporation of thiazole-based building blocks into n-type semiconductors has lagged behind that of other pi-deficient building blocks. Since thiazole insertion into pi-conjugated systems is synthetically more demanding, continuous research efforts are essential to underscore their properties in electron-transporting devices. Here, we report the design, synthesis, and characterization of a new series of thiazolethiophene tetra- (1 and 2) and hexa-heteroaryl (3 and 4) co-oligomers, varied by core extension and regiochemistry, which are end-functionalized with electron-withdrawing perfluorohexyl substituents. These new semiconductors are found to exhibit excellent n-channel OFET transport with electron mobilities (mu(e)) as high as 1.30 cm(2)/(V center dot s) (I-on/I-off > 10(6)) for films of 2 deposited at room temperature. In contrary to previous studies, we show here that 2,2'-bithiazole can be a very practical building block for high-performance n-channel semiconductors. Additionally, upon 2,2'- and 5,5'-bithiazole insertion into a sexithiophene backbone of well-known DFH-6T, significant charge transport improvements (from 0.0010.021 cm(2)/(V center dot s) to 0.200.70 cm(2)/(V center dot s)) were observed for 3 and 4. Analysis of the thin-film morphological and microstructural characteristics, in combination with the physicochemical properties, explains the observed high mobilities for the present semiconductors. Finally, we demonstrate for the first time implementation of a thiazole semiconductor (2) into a trilayer light-emitting transistor (OLET) enabling green light emission. Our results show that thiazole is a promising building block for efficient electron transport in ?-conjugated semiconductor thin-films, and it should be studied more in future optoelectronic applications.

Herein is described a multidisciplinary approach to understand the performance limitations of small molecule organic light emitting transistors (OLETs) based on a layered architecture, an innovative architecture potentially competitive with the state of the art and more flexible for spectral emission control. The processes of charge injection and field-effect transport at metal/organic and organic/organic interfaces are analysed using microscopic and spectroscopic techniques in coordination. Atomic force microscopy and ultrasonic force microscopy are employed to characterize the interface morphology and the initial growth stages of organic films where charge transport actually occurs. X-ray diffraction and near edge X-ray dichroic absorption with linearly polarised light allow to determine the unit cell packing and the molecular orientation at the active organic interfaces, as well as the amount of non-ordered domains. Moreover, chemical reactivity at the interfaces is measured by X-ray photoelectron spectroscopy. It is found that a strong reaction occurs at the metal-organic interfaces, with molecular fragmentation. Additionally, the transport properties strongly depend on the nature of the materials forming the organic stack. Specifically, amorphous conjugated films as bottom layers can promote an increased molecular disorder in the upper active layer, with a concomitant deterioration of the conduction properties.

In this work, we report on the fabrication and characterization of organic light-emitting transistors (OLETs) within an indium–tin-oxide (ITO)-free platform, using graphene-based transparent conductive electrodes in place of ITO as gate electrode. A direct comparison between twin bottom-gate/top-contacts OLETs, where a standard ITO layer is replaced with a film made of a few graphene layers, shows that comparable electrical characteristics can be obtained along with a clear improvement in the electroluminescence generation characteristics. Our experimental findings pave the way to the exploitation of graphene-based transparent conductive electrodes within this class of emerging devices on flexible substrates, further promoting the novel era of flexible organic electronics.

Interest in electronic properties of organic materials has been stimulated by emerging prospects of their application in electronics and photonics [1–4]. Among potential applications, one may envisage use of organic materials as active elements of molecular switches. According to a general definition, a switch is a mechanical, electrical, electronic, or optical device for opening or closing a circuit, or for diverting energy or charge from one part of a circuit to another. In this context, photochromic materials have been extensively studied.

1.1 OLED Vs. OLET Plastic electronics, i.e. electronics based on organic polymer and molecular semiconductors, is a key low-cost technology for new vast application areas. The scope of applications in plastic electronics is virtually endless. It ranges from opto-electronic devices and flexible organic light-emitting diodes (OLEDs) displays, to ultra-cheap, radio-frequency identification tags that can replace the now ubiquitous bar-codes, and to wearable computing and electronic bio-interfaces. The first demonstration of the OLED dates back to the 1960s when electrically driven light emission from non-crystalline organic materials was first observed. After that, several studies were carried out by academic groups and companies (Kodak, Pioneer, Motorola, NEC, etc...) both for fundamental physics comprehension and application purposes. Nowadays electronic products containing displays are becoming more and more portable. Therefore, they need some peculiarities like lightweightness, flexibility, brightness, etc... These, with many others, are the strong points of the OLEDs. In fact they are thinner, lighter and more flexible with respect to their inorganic counterpart. Moreover, OLEDs can be as bright as LEDs and they consume much less power. Due to the organic processability, they are easier to produce and can be made on larger area. Finally OLEDs have large fields of view, about 170 degrees, a significantly advantage over, for example, liquid crystal displays. Of course, these devices present also some disadvantages: they have typically shorter lifetime (in particular lifetime of the blue emitter is critical, about 1.000 hours), they are not very stable and can easily be contaminated by water or oxygen. In general, with respect to OLEDs, organic light-emitting transistors (OLETs) present some fascinating characteristics which overcome many physical and technical drawbacks in the realization of nano-scale integrated electroluminescent devices. The main difference between the vertical (OLED) and planar (OLET) device geometry is a direct consequence of the different device structures. In OLED, charge transport occurs perpendicular to the organic layers (bulk charge transport) while in OLET the transport occurs horizontally (field-effect charge transport). Under the typical biasing conditions, the electron and hole mobility can be about four orders of magnitude higher in OLETs than in OLEDs, thus affecting directly the material lifetime and exciton emission. In a typical OLED structure, the minority carriers travel only few tens

We report on an organic field effect transistor (OFET) with a photochromic dielectric layer, operating as an opto-electrical switch device. The structure contained a photochromic material dissolved in the polymer dielectric metastable forms; poly(methyl methacrylate) was a polymeric layer. The photochromic material was spiropyran exhibiting a large difference of the dipole moments of the stable and insulator; and an n-type perylene derivative was used as the organic semiconductor. Illumination of the structure with UV light resulted in a reversible increase of the source drain current, accompanied by a reversible decrease of the threshold voltage. The initial parameters were restored by a thermal relaxation in the dark or by illumination with visible light. The photoswitching ratio was found to be dependent on the gate voltage ranging between ca. 2 just above the threshold voltage and ca. 1.3 at the highest voltage employed (90 V). The switching has been attributed to reversible changes of dielectric properties of OFET's insulator (dielectric layer) due to a reversible light-triggered reaction of polar photochromic species, dissolved in the bulk of the dielectric layer. The contribution of dipoles aggregated on the semiconductor dielectric interface was estimated to be negligible at gate voltages exceeding ca. 10 V.

In this Article, we present a comprehensive study of organic field-effect transistors (OFETs) made of thin films of methyl, n-butyl, and n-hexyl end-substituted quaterthiophenes on a transparent substrate platform. This particular platform has been already used for organic light-emitting diodes (OLEDs) but rarely employed for OFETs. In perspective, this is a very promising route for the development of field-effect photonic applications such as organic light-emitting transistors (OLETs). A systematic characterization of the organic films has been made by means of atomic force microscopy (AFM) and X-ray diffraction (XRD) to correlate morphology, crystallinity and charge mobility to the alkyl chain length. In particular, a charge mobility value of 0.09 cm(2)/(V s) has been obtained in transparent OFETs with a large area channel for DH4T grown at room temperature. This mobility exceeds the one obtained on silicon-oxide substrates and is likely due to a more favorable interaction of the DH4T molecules with the PMMA layer employed as gate dielectric.

Organic field-effect transistors (OFETs) are alternative emerging device structures for efficient light generation, that could provide a novel architecture to address open issues like exciton-contact and exciton-charge quenching, that still limit the OLEDs efficiency and brightness. Recently, it has been introduced by our research group the model of a tri-layer organic heterostructure implemented in a field-effect configuration, that allows preventing at one time the exciton-metal as well as the exciton-charge quenching in an organic electroluminescence generating device. The device active region is formed by a central optical layer sandwiched between an electron and a hole field-effect conducting film. In order to understand the complex phenomena that happens at the interfaces, with the target to fabricate the most balanced ambipolar structure with high morphological compatibility and high mobility in a vertical heterojunction geometry, we made a preliminary study of a single layer and bi-layer OFET structure composed by ?,?-dihexylquaterthiophene (DH4T) and ?,?-diperfluoroquaterthiophene (DHF4T). By means of this study we showed a new highly balanced ambipolar OFET made of these materials, a first step toward their implementation in a more complex structure as the tri-layer is. © 2010 Elsevier Ltd. All rights reserved.

The potential of organic semiconductor-based devices for light generation is demonstrated by the commercialization of display technologies based on organic light-emitting diodes (OLEDs). Nonetheless, exciton quenching and photon loss processes still limit OLED efficiency and brightness. Organic light-emitting transistors (OLETs) are alternative light sources combining, in the same architecture, the switching mechanism of a thin-film transistor and an electroluminescent device. Thus, OLETs could open a new era in organic optoelectronics and serve as testbeds to address general fundamental optoelectronic and photonic issues. Here, we introduce the concept of using a p-channel/emitter/n-channel trilayer semiconducting heterostructure in OLETs, providing a new approach to markedly improve OLET performance and address these open questions. In this architecture, exciton-charge annihilation and electrode photon losses are prevented. Our devices are >100 times more efficient than the equivalent OLED, >2x more efficient than the optimized OLED with the same emitting layer and >10 times more efficient than any other reported OLETs.

We report on the characteristics of a host-guest lasing system obtained by co-evaporation of an oligo(9,9-diarylfluorene) derivative named T3 with the red-emitter 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran dye (DCM). We demonstrate that the ambipolar semiconductor T3 can be implemented as active matrix in the realization of a host-guest system in which an efficient energy transfer takes place from T3 matrix to the lasing DCM molecules. We performed a spectroscopic study on the system by systematically varying the DCM concentration in the T3 matrix. Measurements of steady-state photoluminescence (PL), PL quantum yield (PLQY) and amplified spontaneous emission (ASE) threshold are used to optimize the acceptor concentration at which the ASE from DCM molecules takes place with the lowest threshold. Organic light-emitting diodes (OLEDs) implementing the DCM:T3 host-guest system as recombination layer are fabricated for verifying the optical properties of the optimised blend in real working devices. Indeed, the very low ASE threshold of T3:DCM makes the investigated blend an appealing system for use as active layer in lasing devices. In particular, the ambipolar charge transport properties of the T3 matrix and its field-effect characteristics make the host-guest system presented here an ideal candidate for the realization of electrically-pumped organic lasers.

In this paper, we present a study of the effects of the influence of the substrate platform on the properties of a three-layer vertical hetero-junction made of thin films of α, ω-diperfluorohexyl-4T (DHF4T), a blend of tris(8-hydroxyquinoline)aluminium (Alq3) and 4-(dicyanomethylene)-2-methyl-6-(p-dimethylaminostyryl)-4H-pyran (DCM) and α, ω-dihexyl-quaterthiophene (DH4T). The hetero-junction represents the active component of an organic light-emitting transistor (OLET). The substrate platforms investigated in this study are glass/indium-tin-oxide/poly(methyl-methacrylate) (PMMA) and Si++/silicon oxide (SiO2)/PMMA. The first platform is almost completely transparent to light and therefore is very promising for use in OLET applications. The second one has been chosen for comparison as it employs standard microelectronic materials, i.e. Si++/SiO2. We show how different gate materials and structure can affect the relevant field-effect electrical characteristics, such as the charge mobility and threshold voltage. By means of an atomic force microscopy analysis, a systematic study has been made in order to correlate the morphology of the active layers with the electrical properties of the devices.