Effect of relative humidity and temperature on the stability of DNTT transistors: A density of states investigation

Za'aba, N. K.; Morrison, John J.; Taylor, David

doi:10.1016/j.orgel.2017.03.002

Cited by 24 publications

(18 citation statements)

References 38 publications

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“…The characteristic decay of the trap DOS into the band gap is in agreement with other reports on vacuum‐deposited films of the organic semiconductor DNTT. [ 40,41 ] The results in Figure 3b show a clear correlation between the surface roughness of the gate dielectric and the density of trap states in the organic semiconductor layer. Figure illustrates the general view of how the roughness of the underlying surface (in this case of the gate dielectric) affects the growth and morphology of the organic semiconductor layer by increasing the degree of structural disorder.…”

Section: Resultsmentioning

confidence: 94%

Effect of the Degree of the Gate‐Dielectric Surface Roughness on the Performance of Bottom‐Gate Organic Thin‐Film Transistors

Geiger

Acharya

Reutter

et al. 2020

Adv Materials Inter

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In organic thin‐film transistors (TFTs) fabricated in the inverted (bottom‐gate) device structure, the surface roughness of the gate dielectric onto which the organic‐semiconductor layer is deposited is expected to have a significant effect on the TFT characteristics. To quantitatively evaluate this effect, a method to tune the surface roughness of a gate dielectric consisting of a thin layer of aluminum oxide and an alkylphosphonic acid self‐assembled monolayer over a wide range by controlling a single process parameter, namely the substrate temperature during the deposition of the aluminum gate electrodes, is developed. All other process parameters remain constant in the experiments, so that any differences observed in the TFT performance can be confidently ascribed to effects related to the difference in the gate‐dielectric surface roughness. It is found that an increase in surface roughness leads to a significant decrease in the effective charge‐carrier mobility and an increase in the subthreshold swing. It is shown that a larger gate‐dielectric surface roughness leads to a larger density of grain boundaries in the semiconductor layer, which in turn produces a larger density of localized trap states in the semiconductor.

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Section: Resultsmentioning

confidence: 94%

Effect of the Degree of the Gate‐Dielectric Surface Roughness on the Performance of Bottom‐Gate Organic Thin‐Film Transistors

Geiger

Acharya

Reutter

et al. 2020

Adv Materials Inter

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“…In previous reports on environmental [24] and bias stress [25] Liguori et al [22] identify excellent light sensitivity and high mobility as the key factors in achieving a high optical response in OTFTs. The latter is confirmed in the review by Baeg et al [7] in which four out of the five highest responsivities reported (10 3 to 10 4…”

Section: Discussionmentioning

confidence: 99%

“…This initial fast response is followed by a slower response from slow hole trapping and/or electron de-trapping, which is not complete during the 100 s period in the dark. The As a final check that the effects we observe are related to interface states, we used the Grünewald model [24,25,35,38] Information show that, an apparent increase in the concentration of deeper states is independent of both the intensity and duration of the illumination, especially following 460 nm illumination. These features are unlikely, therefore, to be associated with bulk state creation in the DNTT.…”

Section: Stress Conditionsmentioning

confidence: 94%

“…We have already undertaken detailed investigations [24,25] into the effects of humidity, temperature and bias stress in DNTT OTFTs based on polystyrene as the dielectric with initial studies [26] on the optical response of DNTT devices fabricated on cross-linked tri(propylene glycol) diacrylate gate insulator buffered with a thin polystyrene layer. Here we report the results of a detailed study into the optical response of DNTT OTFTs on polystyrene, investigating the effects of illumination conditions, i.e.…”

Section: Introductionmentioning

confidence: 99%

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Photo-induced effects in organic thin film transistors based on dinaphtho [2,3-b:2′,3′-f] Thieno[3,2-b′] thiophene (DNTT)

Za'aba

Taylor

2019

Organic Electronics

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We have investigated the photoresponse of organic thin film transistors (OTFTs) based on evaporated films of dinaphtho [2,3-b:2',3'-f] thieno[3,2-b'] thiophene (DNNT) as the active semiconductor and spin-coated polystyrene as the gate insulator. Both during illumination and in subsequent measurements in the dark after long periods under illumination, transfer characteristics shift to more positive gate voltages. The greatest photoresponse was achieved at 460 nm, near the absorption maximum of DNTT. The maximum photosensitivity and photoresponsivity measured were ~10 4 and 1.6 A/W respectively. The latter is the highest reported for an organic semiconductor on a polymeric gate insulator and by suitable adjustments to device geometry could be increased to match the highest reported, ~10 5 A/W, for organic semiconductors. Weaker responses were also obtained when exposed to light from the long-wavelength tail in the absorption spectrum. At these longer wavelengths, the response arises entirely from a shift in flatband voltage caused by deep interface trapping of photo-generated electrons. At 460 nm, however, the positive shift, VON, in turn-on voltage is much greater than the shift, VT, in threshold voltage suggesting that ~3.5 x 10 11 electrons/cm 2 are trapped at the interface at the start of the gate voltage sweep, but ~60% are neutralised by holes from the channel as the device begins to turn on. While the resulting change in subthreshold slope could be interpreted as a change in the density of states (DoS) in the DNTT, this is discounted. Gate bias stress measurements made under illumination, reveal that positive bias enhances interface electron trapping while negative bias reduces the effect owing to the simultaneous trapping of holes from the accumulation channel.

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“…Recently, small molecule semiconductors have got attention for OTFTs, for example dinaphtho[2,3-b:2',3'-f] thieno[3,2-b]thiophene (DNTT) exhibits higher stability than pentacene and P3HT. In addition, extra oxygen-doping enables relatively high mobility [8][9][10][11].…”

Section: Introductionmentioning

confidence: 99%

Roll-to-Roll processable OTFT-based Amplifier and Application for pH sensing

Zhang

Chen

Anastasova

et al. 2019

2019 IEEE 16th International Conference on Wearable and Implantable Body Sensor Networks (BSN)

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The prospect of roll-to-roll (R2R) processable Organic Thin Film Transistors (OTFTs) and circuits has attracted attention due to their mechanical flexibility and low cost of manufacture. This work will present a flexible electronics application for pH sensing with flexible and wearable signal processing circuits. A transimpedance amplifier was designed and fabricated on a polyethylene naphthalate (PEN) substrate prototype sheet that consists of 54 transistors. Different types and current ratios of current mirrors were initially created and then a suitable simple 1:3 current mirror (200nA) was selected to present the best performance of the proposed OTFT based transimpedance amplifier (TIA). Finally, this transimpedance amplifier was connected to a customized needle-based pH sensor that was induced as microfluidic collector for potential disease diagnosis and healthcare monitoring.

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Effect of relative humidity and temperature on the stability of DNTT transistors: A density of states investigation

Cited by 24 publications

References 38 publications

Effect of the Degree of the Gate‐Dielectric Surface Roughness on the Performance of Bottom‐Gate Organic Thin‐Film Transistors

Effect of the Degree of the Gate‐Dielectric Surface Roughness on the Performance of Bottom‐Gate Organic Thin‐Film Transistors

Photo-induced effects in organic thin film transistors based on dinaphtho [2,3-b:2′,3′-f] Thieno[3,2-b′] thiophene (DNTT)

Roll-to-Roll processable OTFT-based Amplifier and Application for pH sensing

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