Development of Organic Field‐effect Transistors for Operation at High Frequency

Perinot, Andrea; Giorgio, Michele; Caironi, Mario

doi:10.1002/9783527804894.ch4

Cited by 10 publications

(9 citation statements)

References 73 publications

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“…Further evidence is provided by the frequency-dependent device admittance as measured by modulating the source terminal of the FET (Figure c). Such frequency-dependent measurements can be employed to evaluate the physical limit to the device operation frequency ( f τ ) as imposed by the carrier transit time . For f < f τ , the carrier velocity is sufficient to follow the modulation, yielding a constant admittance value.…”

Section: Resultsmentioning

confidence: 99%

“…Such frequencydependent measurements can be employed to evaluate the physical limit to the device operation frequency (f τ ) as imposed by the carrier transit time. 53 For f < f τ , the carrier velocity is sufficient to follow the modulation, yielding a constant admittance value. At higher frequencies, however, the admittance will drop due to the limited carrier velocity.…”

Section: Resultsmentioning

confidence: 99%

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Probing Mobile Charge Carriers in Semiconducting Carbon Nanotube Networks by Charge Modulation Spectroscopy

et al. 2020

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Solution-processed networks of semiconducting, single-walled carbon nanotubes (SWCNTs) have attracted considerable attention as materials for next-generation electronic devices and circuits. However, the impact of the SWCNT network composition on charge transport on a microscopic level remains an open and complex question. Here, we use charge-modulated absorption and photoluminescence spectroscopy to probe exclusively the mobile charge carriers in monochiral (6,5) and mixed SWCNT network field-effect transistors. Ground state bleaching and charge-induced trion absorption features, as well as exciton quenching are observed depending on applied voltage and modulation frequency. Through correlation of the modulated mobile carrier density and the optical response of the nanotubes, we find that charge transport in mixed SWCNT networks depends strongly on the diameter and thus bandgap of the individual species. Mobile charges are preferentially transported by small bandgap SWCNTs especially at low gate voltages, whereas large bandgap species only start to participate at higher carrier concentrations. Our results demonstrate the excellent suitability of modulation spectroscopy to investigate charge transport in nanotube network transistors and highlight the importance of SWCNT network composition for their performance.KEYWORDS single-walled carbon nanotubes, networks, charge transport, charge modulation spectroscopy, photoluminescence, trionSemiconducting single-walled carbon nanotubes (SWCNTs) have emerged as a promising material for future electronic applications as they combine high charge carrier mobilities with mechanical flexibility and solution-processability. 1, 2 Stimulated by the major progress in sorting techniques such as gel chromatography, 3, 4 density gradient ultracentrifugation, 5 aqueous two-phase separation, 6 and polymer-wrapping, 7-9 the reproducible fabrication of highperformance field-effect transistors (FETs) and circuits based on networks of purely semiconducting SWCNTs has become feasible. [10][11][12][13][14][15][16] Nonetheless, charge transport in nanotube networks is not yet fully understood especially regarding mixed networks of nanotube species with varying compositions. 17, 18 A detailed understanding of the fundamental transport parameters is necessary to further optimize effective carrier mobilities for competitive network devices at a minimum cost for purification.Charge transport in semiconductors is commonly studied through temperature-dependent measurements of conductivities and carrier mobilities. 17, 19-21 However, these techniques cannot distinguish between different SWCNT species and thus are not suitable to examine the chirality-dependent contributions to the macroscopic device performance. Given the high sensitivity of SWCNT absorption and emission features to charge carriers, which was shown in several studies, 22-25 electro-optical methods could provide additional and even chiralityspecific insights. For example, based on the analysis of the E11 absorption band change of...

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Probing Mobile Charge Carriers in Semiconducting Carbon Nanotube Networks by Charge Modulation Spectroscopy

et al. 2020

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“…While the dynamic performance of a ring oscillator provides a measure of the average switching frequency of the TFTs used in the circuit, more detailed information about the dynamic properties of individual TFTs can be provided by two-port network analysis (2). In particular, scattering-parameter (S-parameter) measurements are attractive for their capability of unambiguously assessing the high-frequency characteristics of organic TFTs (28,29).…”

Section: Two-port Network Analysismentioning

confidence: 99%

“…Flexible electronics (1)(2)(3) are currently a $20-billion-per-year industry driven mainly by the recent trend of manufacturing active-matrix organic light-emitting diode (AMOLED) smartphone displays on polyimide substrates. Of the 600 million AMOLED displays manufactured in 2018, approximately 60% were made on polyimide rather than glass, and this share is projected to further increase (4).…”

Section: Introductionmentioning

confidence: 99%

Flexible low-voltage high-frequency organic thin-film transistors

et al. 2020

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The primary driver for the development of organic thin-film transistors (TFTs) over the past few decades has been the prospect of electronics applications on unconventional substrates requiring low-temperature processing. A key requirement for many such applications is high-frequency switching or amplification at the low operating voltages provided by lithium-ion batteries (~3 V). To date, however, most organic-TFT technologies show limited dynamic performance unless high operating voltages are applied to mitigate high contact resistances and large parasitic capacitances. Here, we present flexible low-voltage organic TFTs with record static and dynamic performance, including contact resistance as small as 10 Ω·cm, on/off current ratios as large as 1010, subthreshold swing as small as 59 mV/decade, signal delays below 80 ns in inverters and ring oscillators, and transit frequencies as high as 21 MHz, all while using an inverted coplanar TFT structure that can be readily adapted to industry-standard lithographic techniques.

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“…Notably, according to recent works, f T in the GHz range is in principle achievable with organic transistors if a series of requirements are met [19]- [21]. Therefore it is not possible to rely further on direct measurement methods for characterizing the upcoming organic high-frequency devices.…”

Section: Introductionmentioning

confidence: 99%

Radio-Frequency Polymer Field-Effect Transistors Characterized by S-Parameters

Giorgio

Caironi

2019

IEEE Electron Device Lett.

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Thanks to recent progress in terms of materials properties, polymer field-effect transistors (FETs) operating in the MHz range can be achieved. However, further development toward challenging frequency ranges, for a field accustomed to slow electronic devices, has to be addressed with suitable device design and measurements methodologies. In this letter, we report n-type FETs based on a solution-processed polymer semiconductor where the critical features have been realized by a large-area compatible direct-writing technique, allowing to obtain a maximum frequency of transition of 19 MHz, as measured by means of Scattering Parameters (S-Parameters). This is the first report of solution-processed organic FETs characterized with S-Parameters.

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Development of Organic Field‐effect Transistors for Operation at High Frequency

Cited by 10 publications

References 73 publications

Probing Mobile Charge Carriers in Semiconducting Carbon Nanotube Networks by Charge Modulation Spectroscopy

Probing Mobile Charge Carriers in Semiconducting Carbon Nanotube Networks by Charge Modulation Spectroscopy

Flexible low-voltage high-frequency organic thin-film transistors

Radio-Frequency Polymer Field-Effect Transistors Characterized by S-Parameters

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