Remarkable Enhancement of the Hole Mobility in Several Organic Small‐Molecules, Polymers, and Small‐Molecule:Polymer Blend Transistors by Simple Admixing of the Lewis Acid p‐Dopant B(C6F5)3

Panidi, Julianna; Paterson, Alexandra F.; Khim, Dongyoon; Fei, Zhuping; Han, Yang; Tsetseris, Leonidas; Vourlias, G.; Patsalas, P.; Heeney, Martin; Anthopoulos, Thomas D.

doi:10.1002/advs.201700290

Cited by 140 publications

(204 citation statements)

References 48 publications

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“…The intentional introduction of molecular dopants has been used extensively to alter the charge transport properties of organic semiconductors, particularly in the area of organic thin‐film transistors (OTFTs) for which some of the highest carrier mobilities have been achieved via this method 6–9. Molecular doping relies on charge transfer interaction(s) between the dopant and the host semiconductor, which ultimately results in formation of free carriers 10,11.…”

Section: Summary Of Operating Parameters Of Solar Cells Based On Pm6:mentioning

confidence: 99%

17.1% Efficient Single‐Junction Organic Solar Cells Enabled by n‐Type Doping of the Bulk‐Heterojunction

et al. 2020

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Molecular doping is often used in organic semiconductors to tune their (opto)electronic properties. Despite its versatility, however, its application in organic photovoltaics (OPVs) remains limited and restricted to p‐type dopants. In an effort to control the charge transport within the bulk‐heterojunction (BHJ) of OPVs, the n‐type dopant benzyl viologen (BV) is incorporated in a BHJ composed of the donor polymer PM6 and the small‐molecule acceptor IT‐4F. The power conversion efficiency (PCE) of the cells is found to increase from 13.2% to 14.4% upon addition of 0.004 wt% BV. Analysis of the photoactive materials and devices reveals that BV acts simultaneously as n‐type dopant and microstructure modifier for the BHJ. Under optimal BV concentrations, these synergistic effects result in balanced hole and electron mobilities, higher absorption coefficients and increased charge‐carrier density within the BHJ, while significantly extending the cells' shelf‐lifetime. The n‐type doping strategy is applied to five additional BHJ systems, for which similarly remarkable performance improvements are obtained. OPVs of particular interest are based on the ternary PM6:Y6:PC71BM:BV(0.004 wt%) blend for which a maximum PCE of 17.1%, is obtained. The effectiveness of the n‐doping strategy highlights electron transport in NFA‐based OPVs as being a key issue.

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Section: Summary Of Operating Parameters Of Solar Cells Based On Pm6:mentioning

confidence: 99%

17.1% Efficient Single‐Junction Organic Solar Cells Enabled by n‐Type Doping of the Bulk‐Heterojunction

et al. 2020

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“…We chose this blend for its spin-coating ease, simplicity and ability to reach extremely high mobilities when incorporated in TG-BC transistor architectures (Figure 1a). [16,17,40] The latter applicability to TG-BC device architectures is well known for such solution processed small-molecule/polymer blends because of the vertical phase separation between the two organic components, leaving a layer of high-mobility small molecule at the surface/ air interface and hence the transistor channel. [41] To this end, the use of the TG-BC OTFT architecture is an essential component to this study, ensuring that the semiconducting channel interface with the different dielectrics remain identical.…”

Section: Resultsmentioning

confidence: 99%

“…[8] These points are important if OTFTs are ever to be used in integrated circuits (ICs), where IC operating frequencies can be increased by reducing the channel length and improving µ. [11,12] Therefore, much research has focused on techniques that improve this energetic mismatch, such as contact doping, [13][14][15] alternative contact materials, OSC doping, [4,16,17] injection layers, [18,19] and self-assembled monolayer (SAM) treatments. [9] In principle, these requirements can be met by reducing R C .…”

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Impact of the Gate Dielectric on Contact Resistance in High‐Mobility Organic Transistors

Paterson

Mottram

Faber

et al. 2019

Adv Elect Materials

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the greatest focus placed on improving the charge-carrier mobility (µ). [1][2][3][4][5] However, these successful improvements in µ will be in vain unless other important operating parameters are also improved. One particularly weak point in OTFTs that use undoped, wide-bandgap organic semiconductors (OSCs) is contact resistance (R C ). Not only are the µ values reported for OTFTs suffering from R C at a high risk of being overestimated or underestimated, [1,6,7] but a large R C can also prevent OTFT miniaturization. [8] These points are important if OTFTs are ever to be used in integrated circuits (ICs), where IC operating frequencies can be increased by reducing the channel length and improving µ. [9,10] Indeed, Hagen Klauk recently calculated two key requirements for OTFTs to be used in GHz frequency applications for the "internet of things": i) R C less than 100 Ωcm and ii) channel dimensions either equal to or less than 1 µm. [9] In principle, these requirements can be met by reducing R C . Although R C is extracted as a single value from the OTFT output characteristics, its magnitude encompasses different aspects of OTFT operation. The largest contributor to R C is the potential energy difference between the metal contact and the OSC. In OTFTs, this energetic difference typically creates a Schottky barrier, which reduces how efficiently charge carriers are injected into/extracted from the OTFT channel. [11,12] Therefore, much research has focused on techniques that improve this energetic mismatch, such as contact doping, [13][14][15] alternative contact materials, OSC doping, [4,16,17] injection layers, [18,19] and self-assembled monolayer (SAM) treatments. [20,21] However, there are a number of additional factors that influence the magnitude of R C , including the OSC microstructure, [22,23] charge trapping at the metal/OSC interface, [24] as well as the type of dielectric materials employed [25,26] and the microstructure they create at the OSC/dielectric interface.The dielectric layer in OTFTs has attracted significant attention over the years for a variety of reasons. For instance, the all-important charge accumulated channel forms within a few nanometers of the OSC/dielectric interface. [27,28] Also, the dielectric influences numerous OTFT parameters, such as operating voltage, [29] threshold voltage, [30,31] on-off current, [32] subthreshold swing/slope, [33] hysteresis, [34] mobility, [35] and operational stability. [36,37] However, the relationship between the The impact of the gate dielectric on contact resistance in organic thin-film transistors (OTFTs) is investigated using electrical characterization, biasstress stability measurements, and bandgap density of states (DOS) analysis. Two similar dielectric materials, namely Cytop and poly[4,5-difluoro-2,2bis(trifluoromethyl)-1,3-dioxole-co-tetrafluoroethylene] (Teflon AF2400), are tested in top-gate bottom-contact OTFTs. The contact resistance of Cytopbased OTFTs is found to be greater than that of the AF2400-based devices, even though the metal/OSC...

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“…These dopants either have a very deep lowest unoccupied molecule orbitals (LUMO) (p‐dopants) or a very shallow highest occupied molecule orbitals (HOMO) (n‐dopants), and can effectively dope the semiconductors by forming ion‐pairs or charge transfer complex 32. In the past few years, the dopants and doping techniques for organic semiconductors have been progressed tremendously, with novel dopants like Lewis acid (for p‐doing) and Lewis base (for n‐doping) demonstrating significant doping effects for improving performance in OFETs or OPVs 33–36. However, these new doping techniques have not been fully implemented for OTE applications, and therefore it is worth exploring novel dopants to further enhance the thermoelectric performance of OTEs.…”

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confidence: 99%

“…The ESR results further confirm that doping occurs when TrTPFB is blended with PCDTPT. Furthermore, we have also attempted to dope PCDTPT with two other commonly used dopants: F 4 TCNQ and B(C 6 F 5 ) 3 20,22,33,40. It turns out that the doping effect of the two dopants are much weaker than that of TrTPFB (see Figures S3 and S4, Supporting Information), indicating TrTPFB is more preferred as the dopant to PCDTPT.…”

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confidence: 99%

Doping High‐Mobility Donor–Acceptor Copolymer Semiconductors with an Organic Salt for High‐Performance Thermoelectric Materials

Guo

Reith

et al. 2020

Adv Elect Materials

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Organic semiconductors (OSCs) are attractive for fabrication of thermoelectric devices with low cost, large area, low toxicity, and high flexibility. In order to achieve high‐performance organic thermoelectric devices (OTEs), it is essential to develop OSCs with high conductivity (σ ), large Seebeck coefficient (S), and low thermal conductivity (κ ). It is equally important to explore efficient dopants matching the need of thermoelectric devices. The thermoelectric performance of a high‐mobility donor–acceptor (D–A) polymer semiconductor, which is doped by an organic salt, is studied. Both a high p‐type electrical conductivity approaching 4 S cm−1 and an excellent power factor (PF) of 7 µW K−2 m−1 are obtained, which are among the highest reported values for polymer semiconductors. Temperature‐dependent conductivity, Seebeck coefficient and power factor of the doped materials are systematically investigated. Detailed analysis on the results of thermoelectric measurements has revealed a hopping transport in the materials, which verifies the empirical relationship: S ∝ σ−1/4 and PF ∝ σ1/2. The results demonstrate that D–A copolymer semiconductors with proper combination of dopants have great potential for fabricating high‐performance thermoelectric devices.

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Remarkable Enhancement of the Hole Mobility in Several Organic Small‐Molecules, Polymers, and Small‐Molecule:Polymer Blend Transistors by Simple Admixing of the Lewis Acid p‐Dopant B(C₆F₅)₃

Cited by 140 publications

References 48 publications

17.1% Efficient Single‐Junction Organic Solar Cells Enabled by n‐Type Doping of the Bulk‐Heterojunction

17.1% Efficient Single‐Junction Organic Solar Cells Enabled by n‐Type Doping of the Bulk‐Heterojunction

Impact of the Gate Dielectric on Contact Resistance in High‐Mobility Organic Transistors

Doping High‐Mobility Donor–Acceptor Copolymer Semiconductors with an Organic Salt for High‐Performance Thermoelectric Materials

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