Interface engineering to enhance charge injection and transport in solution-deposited organic transistors

Mei, Yaochuan; Fogel, Derek; Chen, Jihua; Ward, Jeremy W.; Payne, Marcia M.; Anthony, John E.; Jurchescu, Oana D.

doi:10.1016/j.orgel.2017.07.032

Cited by 43 publications

(62 citation statements)

References 34 publications

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“…Therefore, not only does the SAM create higher electrode work function, and larger crystal domains, but it induces ordering that aligns the high‐mobility crystal direction with the plane of the channel. Analogous results have been obtained when this organic semiconductor was deposited on electrodes treated with TFBT or TTFP . Kim et al showed that a low carrier density zone in the semiconductor near the contact interface makes a large contribution to contact resistance in coplanar devices .…”

Section: Reducing Contact Resistance: Electrode Design and Beyondsupporting

confidence: 57%

“…It is also a fluorine‐substituted SAM but containing five –F atoms on the benzene structure, and it can increase the work function of gold by up to 0.8 eV . Other heavily fluorinated SAMs include 4‐(tri‐ fluoromethyl)‐benzenethiol (TFBT) and 2,3,5,6‐tetrafluoro‐4‐(trifluoromethyl)‐ benzenethiol (TTFP), which were shown to increase the work function, lower contact resistance, and improve OFET performance, as seen in Figure d . While the fluorinated SAMs are popular choices for increasing the work function, several SAMs have been successfully adopted to reduce the work function.…”

Section: Reducing Contact Resistance: Electrode Design and Beyondmentioning

confidence: 99%

Section: Reducing Contact Resistance: Electrode Design and Beyondmentioning

confidence: 99%

“…A challenging aspect of adopting SAM treatment for work function tuning is that their presence also modifies the surface energy and chemistry, thus sometimes leading to changes in the microstructure of the semiconductor film, which can have a profound impact on contact resistance, channel resistance and overall device performance . A well‐studied type of SAM‐mediated microstructure change is that resulting from interactions between fluorinated SAMs and polyacene‐based molecules.…”

Section: Reducing Contact Resistance: Electrode Design and Beyondmentioning

confidence: 99%

See 3 more Smart Citations

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Waldrip

Jurchescu

Gundlach

et al. 2019

Adv Funct Materials

Self Cite

219

261

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Organic semiconductors have sparked interest as flexible, solution processable, and chemically tunable electronic materials. Improvements in charge carrier mobility put organic semiconductors in a competitive position for incorporation in a variety of (opto-)electronic applications. One example is the organic field-effect transistor (OFET), which is the fundamental building block of many applications based on organic semiconductors. While the semiconductor performance improvements opened up the possibilities for applying organic materials as active components in fast switching electrical devices, the ability to make good electrical contact hinders further development of deployable electronics. Additionally, inefficient contacts represent serious bottlenecks in identifying new electronic materials by inhibiting access to their intrinsic properties or providing misleading information. Recent work focused on the relationships of contact resistance with device architecture, applied voltage, metal and dielectric interfaces, has led to a steady reduction in contact resistance in OFETs. While impressive progress was made, contact resistance is still above the limits necessary to drive devices at the speed required for many active electronic components. Here, the origins of contact resistance and recent improvement in organic transistors are presented, with emphasis on the electric field and geometric considerations of charge injection in OFETs.semiconductors with superior intrinsic charge transport properties, there is a stringent need to improve the device properties in order to allow organic devices to fulfill their technological prospectives. In the organic semiconductor community, contact resistance (R C ) has come under increased scrutiny as it is apparent that the final device performance is often domi nated by carrier injection, rather than the transport through the semiconductor layer. Contact resistance can impact OFET development in multiple ways. First, if not accounted for, a high contact resistance may lead to inaccurate extraction of the device parameters. Second, any inaccuracies in parameter extraction can have significant consequences on material development, from generating incorrect structure-property relationships to discarding organic semiconductors whose efficient intrinsic electrical properties have been masked by inefficient contacts. Beyond OFET and semiconductor characterization, analog, low power, and high frequency applications require a greater level of device parameter control than has been obtained in typical DC, high-voltage OFETs. For analog applications, e.g., integration of conditioning circuits such as local sense amps for distributed flexible sensor arrays, nonlinearity of the transistor response inhibits proper functioning and limits applicability of common models used to design circuitry. Low power device development for novel materials are hindered by the high voltage turn-on and current suppression in devices with large R C . Considering high-frequency applications, Klauk suggest...

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Section: Reducing Contact Resistance: Electrode Design and Beyondsupporting

confidence: 57%

Section: Reducing Contact Resistance: Electrode Design and Beyondmentioning

confidence: 99%

Section: Reducing Contact Resistance: Electrode Design and Beyondmentioning

confidence: 99%

Section: Reducing Contact Resistance: Electrode Design and Beyondmentioning

confidence: 99%

See 2 more Smart Citations

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Waldrip

Jurchescu

Gundlach

et al. 2019

Adv Funct Materials

Self Cite

219

261

View full text Add to dashboard Cite

show abstract

“…In the past, the impact of contact effects was treated by many research groups [11][12][13][14][15][16][17][18][19][20][21]. Recently, many efforts were also done on reducing the contact effects, such as testing different materials as contact electrodes [22,23], the insertion of layers at the metal-semiconductor interface [24,25], or the use of molecular doping [26]; and also on working toward an universal compact model of organic transistor technologies that includes the contact effects [27].…”

Section: Introductionmentioning

confidence: 99%

Versatile model for the contact region of organic thin-film transistors

Romero

González

Deen

et al. 2020

Organic Electronics

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Contact effects in organic thin film transistors (OTFTs) remain an important problem to be solved in these devices. Therefore, the correct physio-chemical modeling of the contact regions in OTFTs is necessary. In this work, a standard model for the contact region of OTFTs is proposed. It is a versatile model that describes the current-voltage characteristics of different kinds of contacts. It reproduces the behavior of Schottky barrier or space-charge limited contacts. It is a simple unified model since only a single parameter is necessary in order to distinguish between both kinds of contacts. The model is easily integrated in a generic compact model for the current-voltage characteristics of OTFTs. The resulting compact model, used in combination with an evolutionary parameter extraction procedure, allows to extract the intrinsic parameters and the current-voltage curves at the contact of single short-channel transistors. There is no need to use transistors with multiple channel lengths to accurately characterize the contact region or the active channel of the transistor. The model is tested with published experimental data of OTFTs with Schottky barrier or space-charge limited contacts. Finally, the method has been used as a diagnostic tool to analyze how an ammonia sensor reacts to different concentrations of the ammonia gas. Interestingly, alterations in the contact region have been detected when the gas concentration varies, transforming the space-charge limited contact of a pristine OTFT into a Schottky barrier contact under the exposure of gas.

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Tuning Interfacial Properties by Spontaneously Generated Organic Interlayers in Top‐Contact‐Structured Organic Transistors

Choi

Seo

et al. 2020

Adv Funct Materials

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Controlling the interfacial properties between the electrode and active layer in organic field‐effect transistors (OFETs) can significantly affect their contact properties, resulting in improvements in device performance. However, it is difficult to apply to top‐contact‐structured OFETs (one of the most useful device structures) because of serious damage to the organic active layer by exposing solvent. Here, a spontaneously controlled approach is explored for optimizing the interface between the top‐contacted source/drain electrode and the polymer active layer to improve the contact resistance (RC). To achieve this goal, a small amount of interface‐functionalizing species is blended with the p‐type polymer semiconductor and functionalized at the interface region at once through a thermal process. The RC values dramatically decrease after introduction of the interfacial functionalization to 15.9 kΩ cm, compared to the 113.4 kΩ cm for the pristine case. In addition, the average field‐effect mobilities of the OFET devices increase more than three times, to a maximum value of 0.25 cm2 V−1 s−1 compared to the pristine case (0.041 cm2 V−1 s−1), and the threshold voltages also converge to zero. This study overcomes all the shortcomings observed in the existing results related to controlling the interface of top‐contact OFETs by solving the discomfort of the interface optimization process.

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Interface engineering to enhance charge injection and transport in solution-deposited organic transistors

Cited by 43 publications

References 34 publications

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Contact Resistance in Organic Field‐Effect Transistors: Conquering the Barrier

Versatile model for the contact region of organic thin-film transistors

Tuning Interfacial Properties by Spontaneously Generated Organic Interlayers in Top‐Contact‐Structured Organic Transistors

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