Temporal and thermal properties of optically induced instabilities in P3HT field-effect transistors

Kehrer, Lorenz A.; Winter, Stefan; Fischer, R. A.; Melzer, Christian; Seggern, Heinz von

doi:10.1016/j.synthmet.2011.08.007

Cited by 22 publications

(14 citation statements)

References 20 publications

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“…Using the threshold voltage ܸ ௧ of -4.8 V and the relation ܰ ௧ ൌ ‫ܥ‬ • ܸ ௧ ሺ݁ • ݀ሻ ⁄ a low interface trap density ܰ ௧ of 2.26·10 11 cm -2 has been estimated. This is in accordance to values reported for the parent uncross-linked analogue PMMA (4.2·10 11 cm -2 [34], (0.2-10)·10 11 cm -2 [35]) and PS (6.93·10 11 cm -2 [36]). Although the field effect mobility in the saturation regime is not so high (0.04 cm²V -1 s -1 ), the leakage currents are at least three orders of magnitude lower than the drain current which confirms the good dielectric properties of cross-linked PAZ 14.…”

Section: Characterization Of Ofet-devicessupporting

confidence: 91%

“…However, due to the thinner layer thickness of the PAZ 12 dielectrics the interface trap density is calculated to be 2.65·10 11 cm -2 and 2.92·10 11 cm -2 for the 150 nm and 92 nm thick layer, respectively. This turns out to be in the same order of magnitude as for the PAZ 14-based device which is in accordance with OFETs with non-cross-linked PMMA dielectric 34,35 . From the drain currents of the PAZ 12 devices the mobility can be calculated by the Shockley equations.…”

Section: Characterization Of Ofet-devicessupporting

confidence: 82%

“…Although the relations between dielectric surface properties and electrical performance of organic semiconductors are not fully understood yet, it has been shown that smooth and non-polar surfaces are beneficial for the performance of p-type semiconductors in OFETs. [31][32][33][34] In this sense, the smooth and hydrophobic cross-linked polymers provide dielectric surfaces compatible with pentacene deposition. Figure 4b shows the morphology of pentacene layers deposited on PAZ 14 and PAZ 12 double layers, respectively.…”

Section: Surface and Dielectric Characterization Of Cross-linked Dielmentioning

confidence: 99%

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Cross-linkable random copolymers as dielectrics for low-voltage organic field-effect transistors

et al. 2015

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A large number of cross-linkable dielectrics with good dielectric properties have been reported; however, all of them suffer from disadvantages like uncontrolled pre-crosslinking, necessity of high process temperatures and the need for an additional cross-linking compound. In this contribution, two new poly(methyl methacrylate) polymers are introduced which can be cross-linked due to the attached benzyl azide (N3) monomer units making the addition of hardeners or initiators obsolete. The synthesis of the copolymers as well as their successful characterization and usage as gate dielectrics for organic field-effect transistors is demonstrated. The investigated polymers have been labeled PAZ 12 and PAZ 14 according to their azide content in mol%. The additional building blocks of the polymers are methyl methacrylate for PAZ 12 and methyl methacrylate and styrene monomer units in about an equal ratio for PAZ 14. Spin-coated thin films were cross-linked by a thermal treatment at 110 °C followed by an UV exposure at a wavelength of 254 nm yielding insoluble, smooth and electrically dense polymeric networks. Optimal cross-linking parameters were obtained using infrared spectroscopy to follow the N3 vibrational mode. Its disappearance confirms a complete cross-linking reaction, and thus fully reacted azide groups facilitate the analytics. The dielectric properties of the cross-linked thin films have been studied by impedance spectroscopy. The application of double layer dielectrics results in lower dielectric losses and lower leakage currents in the subsequently produced pentacene-based field-effect transistors. These devices operate at voltages below −6 V and show hysteresis-free current–voltage characteristics with hole mobilities up to 0.16 cm2 V−1 s−1. PAZ 12 appears to be superior to PAZ 14 due to a lower total layer thickness of down to 92 nm still providing good insulation in the transistor presumably related to a lower free volume that arises in the cross-linked network of the two-component containing copolymer PAZ 12

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Section: Characterization Of Ofet-devicessupporting

confidence: 91%

Section: Characterization Of Ofet-devicessupporting

confidence: 82%

Section: Surface and Dielectric Characterization Of Cross-linked Dielmentioning

confidence: 99%

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Cross-linkable random copolymers as dielectrics for low-voltage organic field-effect transistors

et al. 2015

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“…Later, a CTC between P3HT and molecular oxygen was reported, and evidence for doped P3HT species was found 69. Unintentional CP doping by molecular oxygen can decrease the performance of organic transistors69a,70 and solar cells,71 and thus, should be avoided. In contrast, controllable CP doping by organic molecules, that is, organic doping, could be a promising approach for tuning the electronic properties of CP films.…”

Section: Ground Statementioning

confidence: 99%

Charge‐Transfer Complexes of Conjugated Polymers

Sosorev

Paraschuk

2014

Israel Journal of Chemistry

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Donoracceptor blends of conjugated polymers (CPs) are workhorse materials for the state‐of‐the‐art polymer solar cells. Although earlier it was suggested that charge transfer in these blends occurred only in the excited electronic state, a body of evidence for ground‐state charge transfer and the corresponding charge‐transfer complex (CTC) formation has been reported in the last decade. In some CP:acceptor blends, the CTC is pronounced and can be noticed visually as a colour change, while in more common CP:fullerene blends it is very weak. However, in both, the CTC governs charge separation, which is the key photophysical process for organic solar cells, through so‐called charge‐transfer states. Moreover, the pronounced CTC can substantially modify the blend properties: extend the blend absorption in the red and infrared regions, change the morphology to facilitate donoracceptor intermixing, stimulate polymer self‐organization and ordering, and increase the polymer photooxidation stability. Addition of one of the strongest organic acceptors, 2,3,5,6‐tetrafluoro‐7,7,8,8‐tetracyanoquinodimethane (F4‐TCNQ), to the CP:fullerene blend is an example of organic doping (a CTC with full charge transfer), improving the blend structural and electronic properties and finally the solar cell performance. In this review, we summarize the current knowledge on CTCs in various CP:acceptor blends and the impact of CTC on the blend properties and the device performance.

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“…The crystallization of the film out of the melt provides a time effective, reproducible preparation method for OFETs with a device performance that easily competes with the performance of devices produced by the more time consuming and complex crystal growth . This straight forward post‐deposition treatment enhances OFETs to a performance comparable to that of P3HT devices and PPE devices fabricated by much more elaborate film forming processes.…”

Section: Introductionmentioning

confidence: 99%

Improved Thin‐Film Transistor Performance Through a Melt of Poly(para‐phenyleneethynylene)

Schmid

Kast

Schröder

et al. 2014

Macromol. Rapid Commun.

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The performance of polymer field-effect transistors (PFETs) based on short rigid rod semiconducting poly(2,5-didodecyloxy-p-phenyleneethynylene) (D-OPPE) is highlighted. The controlled heating and cooling of thin films of D-OPPE allows for a recrystallization from the melt, boosting the performance of D-OPPE-based transistors. The improved film properties induced by controlled annealing lead to a hole field-effect mobility around 0.014 cm V s , an on/off ratio of 10 , a sub-threshold swing of 3 V dec and a threshold voltage of -35 V, employing a poly(methyl methacrylate) (PMMA) gate dielectric. Thus, PFETs out of D-OPPE compete now with spin-coated, polycrystalline poly(3-hexylthiophene)-based PFETs.

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Temporal and thermal properties of optically induced instabilities in P3HT field-effect transistors

Cited by 22 publications

References 20 publications

Cross-linkable random copolymers as dielectrics for low-voltage organic field-effect transistors

Cross-linkable random copolymers as dielectrics for low-voltage organic field-effect transistors

Charge‐Transfer Complexes of Conjugated Polymers

Improved Thin‐Film Transistor Performance Through a Melt of Poly(para‐phenyleneethynylene)

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