Improved Performance in n‐Type Organic Field‐Effect Transistors via Polyelectrolyte‐Mediated Interfacial Doping

Park, Yu Jung; Joo, Myoung; Yoon, Yung Jin; Cho, Shinuk; Kim, Jin Young; Seo, Jung Hwa; Walker, Bright

doi:10.1002/aelm.201700184

Cited by 21 publications

(16 citation statements)

References 32 publications

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“…This surface dipole reduces the energy which is required to remove an electron from the lm surface and thus reduces the effective WF, an effect which has been well documented. 33,36 The electronic structures of the interlayers were further investigated by UPS. Fig.…”

Section: Resultsmentioning

confidence: 99%

“…An efficiency of 6.3% was reported for inverted devices based on a PTB7 active layer, comparable to results using CPE interfacial layers. 36 Although it appears that the ionic character of NPEs allows them to have similar effects on the band structure of semiconducting devices as CPEs, the range of NPE materials studied so far has remained very limited and further studies are necessary to understand how different ionic functionalities in NPEs affect the band structure of semiconducting devices.…”

Section: Introductionmentioning

confidence: 99%

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Effect of counter-ions on the properties and performance of non-conjugated polyelectrolyte interlayers in solar cell and transistor devices

et al. 2019

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Effect of counter-ions on the properties and performance of non-conjugated polyelectrolyte interlayers in solar cell and transistor devices

et al. 2019

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“…Park et al have incorporated halogen ions into the PEIE that yields the nonconjugated polyelectrolyte of PEIEH + X (X = Cl − , Br − , and I − ) and PEIEH + X can dope PCBM films. With Au as the electrode, electron injection is improved after PEIEH + X is inserted between the PCBM and Au electrode.…”

Section: Surface Modifiersmentioning

confidence: 99%

Low Work Function Surface Modifiers for Solution‐Processed Electronics: A Review

Peng

Qin

et al. 2018

Adv Materials Inter

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electron injection or extraction, whereas a high work function metal such as Au is employed for hole injection or extraction. Since the low work function metallic electrodes are normally chemically reactive, they are readily oxidized in air (oxygen) and water when serving as cathodes. Airstable electrodes with a low work function are more challenging compared to ones with a high work function. Figure 1 shows the physics of band bending when a metal electrode is in contact with an n-type semiconductor to illustrate the importance of a low work function for the electrode. When the work function (WF = E vac − E F ) of the metal electrode is larger than that of the n-type semiconductor, electron flows from the semiconductor to the metal electrode. Unfavorable band bending for electron collection is formed at the interface in this case. By contrast, if the work function of the metal electrode is lower than that of the n-type semiconductor (Figure 1b), the opposite band bending is formed to favor electron collection from the semiconductor to the electrode. Therefore, an electrode with a sufficiently low work function is crucial to efficient electron injection or collection. Surface modification has been shown to be effective in reducing the work function of the electrodes to facilitate electron injection and collection, [7] and enhanced electron collection or injection improves the performance of organic electron devices. The proper surface modification strategy can produce air-stable electron collection or injection electrodes combined with high work function electrode/surface modifiers. This approach also enables diverse design of novel-device architectures for flexible electronics and printed electronics.Several types of low work function surface modifiers have been developed for the cathode interface. Inorganic metal oxides and alkali metal salts are effective low work function modifiers. N-type metal oxides such as titanium oxide (TiO x ) [8] and zinc oxide (ZnO) [9] are often used as cathode interlayers due to the excellent charge mobility and electron selectivity. The metal oxide film with a typical thickness of more than 10 nm possesses a low work function when coating on a high work function electrode and high-temperature annealing is normally required. Alkali metal salts like LiF, [10] Cs 2 CO 3 , [11] and Li 2 CO 3 [12] can also be incorporated into the cathode interlayer to reduce the electrode work function. Considering the intrinsic insulating properties, the thickness must be carefully controlled to ensure efficient electron extraction and injection. Another example is organic molecules grafted with ionic or polar Interfaces with a low work function are crucial to electron injection and collection in semiconducting devices such as diodes and transistors, and many types of surface modifiers have been developed to tailor the work functions of electronic devices. In this review, the basic and working mechanisms of low work function surface modifiers covering the surface dipole, low intrinsic bulk work funct...

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“…Polymer-based interfacial materials have been shown to form dipoles on ITO electrodes which allows ϕ to be adjusted [21]. Conjugated polyelectrolytes (CPEs) have been used extensively to lower the work function of electrodes in organic semiconducting devices [22][23][24], and nonconjugated polyelectrolytes (NPEs) [25,26] are representative types of polymers which may be used for this purpose [5,27,28]. CPEs are based on repeating aromatic backbones but have the disadvantage that the conjugated, aromatic backbone is costly to synthesize and may introduce extraneous electronic effects, whereas NPEs can be synthesized simply and inexpensively, and allow the effects of ionic groups to be investigated without interference from a conjugated backbone [29][30][31].…”

Section: Introductionmentioning

confidence: 99%

Hybrid Lead-Halide Polyelectrolytes as Interfacial Electron Extraction Layers in Inverted Organic Solar Cells

et al. 2020

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A series of lead-halide based hybrid polyelectrolytes was prepared and used as interfacial layers in organic solar cells (OSCs) to explore their effect on the energy band structures and performance of OSCs. Nonconjugated polyelectrolytes based on ethoxylated polyethylenimine (PEIE) complexed with PbX2 (I, Br, and Cl) were prepared as polymeric analogs of the perovskite semiconductors CH3NH3PbX3. The organic/inorganic hybrid composites were deposited onto Indium tin oxide (ITO) substrates by solution processing, and ultraviolet photoelectron spectroscopy (UPS) measurements confirmed that the polyelectrolytes allowed the work function of the substrates to be controlled. In addition, X-ray photoelectron spectroscopy (XPS) results showed that Pb(II) halide complexes were present in the thin film and that the Pb halide species did not bond covalently with the cationic polymer and confirmed the absence of additional chemical bonds. The composite ratio of organic and inorganic materials was optimized to improve the performance of OSCs. When PbBr2 was complexed with the PEIE material, the efficiency increased up to 3.567% via improvements in open circuit voltage and fill factor from the control device (0.3%). These results demonstrate that lead-halide based polyelectrolytes constitute hybrid interfacial layers which provide a novel route to control device characteristics via variation of the lead halide composition.

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Improved Performance in n‐Type Organic Field‐Effect Transistors via Polyelectrolyte‐Mediated Interfacial Doping

Cited by 21 publications

References 32 publications

Effect of counter-ions on the properties and performance of non-conjugated polyelectrolyte interlayers in solar cell and transistor devices

Effect of counter-ions on the properties and performance of non-conjugated polyelectrolyte interlayers in solar cell and transistor devices

Low Work Function Surface Modifiers for Solution‐Processed Electronics: A Review

Hybrid Lead-Halide Polyelectrolytes as Interfacial Electron Extraction Layers in Inverted Organic Solar Cells

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