Long-lived persistent currents in poly(3-octylthiophene) thin film transistors

Lutsyk, Petro; Janus, Krzysztof; Mikołajczyk, Mikołaj M.; Sworakowski, J.; Boratyński, B.; Tłaczała, M.

doi:10.1016/j.orgel.2009.12.003

Cited by 14 publications

(15 citation statements)

References 22 publications

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“…In successive pulses, the amplitude of the response increased but on a steadily increasing background -the 100 s dark period was insufficient to return the device to the initial condition. This is an example of persistent photoconductivity reported by several others workers[31][32][33].When the device was biased into the on state (VG = -40 V, VD = -1 V), as seen in…”

supporting

confidence: 67%

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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confidence: 67%

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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“…These values are comparable to previous untreated PVP-based transistors [34,[49][50][51]. Differences in performance after stress can be related to accentuated trapping from hydroxyl groups at the PVP backbone [31,38]. According to Choi et al, new trapping sites can be created because of water molecules adsorbed to the semiconducting film [52].…”

Section: B Current Versus Voltage Shifts Under Stresssupporting

confidence: 69%

“…A greater VT was observed for PVP:PMF on glass, since the organic dielectric is thicker (830 nm) compared to SiO2 (300 nm) [38]. Positive VT values are related to doping by O2 in the atmosphere [2,25,31,32]. A higher trapping is to be expected at the semiconductor/dielectric interface on glass, since the effective mobility is one order of magnitude lower and the subthreshold slope 20 % higher.…”

Section: A Pristine Transistor Performance On Both Substratesmentioning

confidence: 96%

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Bias Stress in Organic Thin-Film Transistors Towards Low-Cost Flexible Gas Sensors

Izquierdo

Oliveira

Nogueira

et al. 2021

JICS

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This work is focused on the bias stress (BS) effects in Organic Thin-Film Transistors (OTFTs) from poly(2,5-bis(3-alkylthiophen-2-yl)thieno[3,2-b]thiophene) (PBTTT-C14) on both highly-doped Si and glass substrates. While the former had a thermally-grown SiO2 dielectric, the latter demanded an alternative dielectric that should be capable to withstand bottom contact lithography, as well as semiconducting thin-film deposition. In addition, it should represent one more step towards flexible electronics. In order to do that, poly(4-vinylphenol) (PVP) was blended to poly(melamine-co-formaldehyde) methylated (PMF). OTFTs on glass with a cross-linked polymer dielectric had a charge carrier mobility (μ) of 4.0x10-4 cm2/Vs, threshold voltage (VT) of 18 V, current modulation (ION/OFF) higher than 1x102, and subthreshold slope (SS) of -7.7 V/dec. A negative BS shifted VT towards negative values and produced an increase in ION/OFF. A positive BS, on the other hand, produced the opposite effect only for OTFTs on Si. This is believed to be due to a higher trapping at the PVP:PMF interface with PBTTT-C14. Modeling the device current along time by a stretched exponential provided shorter time constants of ca. 105 s and higher exponents of 0.7–0.9 for devices on glass. Due to the presence of increased BS effects, the application of organic TFTs based on PVP:PMF as flexible sensors will require compensating circuits, lower voltages or less measurements in time. Alternatively, BS effects could be reduced by a dielectric surface treatment.

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“…More recently, Kim et al explained the persistent photocurrent in dihexylquarterthiophene (DH4T) organic transistor with a slow detrapping of photogenerated carriers and they observed that the gate electric field could accelerate this detrapping process [32]. A similar phenomenon was reported by Lutsyk et al on the study of poly(3-octylthiophene) (P3OT) transistor and they also emphasized the role of gate bias for erasing the memory effect [33]. Despite the dissimilarities in the material and/or the device geometry, it is likely that these results can help interpret our observation.…”

Section: Circuit Parameters During Relaxationsupporting

confidence: 52%

Persistent photoexcitation effect on the poly(3-hexylthiophene) film: Impedance measurement and modeling

et al. 2012

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International audienceWe report on the equivalent circuit modeling of the relaxation behavior of an optically excited thick poly(3-hexylthiophene) (P3HT) film by means of impedance spectroscopy. Fabricated metal-semiconductor-metal devices with Au electrodes showed a nearly perfect ohmic behavior under ambient conditions. Impedance measurements on illuminated P3HT device showed a dramatical decrease of the impedance modulus under illumination and very slow relaxation to the initial state. Impedance-frequency data obtained during relaxation could not be explained by a simple parallel resistance-capacitance circuit but it could be best fitted by incorporating a constant-phase element instead of a normal capacitance. By observing the variation of the circuit parameters, it is found that the relaxation process is dominated by slow recombination (elimination) of the excess photogenerated carriers, which is confirmed by the time-varying photoconductivity of the device

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Long-lived persistent currents in poly(3-octylthiophene) thin film transistors

Cited by 14 publications

References 22 publications

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

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

Bias Stress in Organic Thin-Film Transistors Towards Low-Cost Flexible Gas Sensors

Persistent photoexcitation effect on the poly(3-hexylthiophene) film: Impedance measurement and modeling

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