Passivation of trap states in unpurified and purified C60 and the influence on organic field-effect transistor performance

Olthof, Selina; Singh, Sanjeev; Mohapatra, Swagat K.; Barlow, Stephen; Marder, Seth R.; Kippelen, Bernard; Kahn, Antoine

doi:10.1063/1.4772551

Cited by 66 publications

(68 citation statements)

References 32 publications

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“…Alternatively, the shift of the threshold voltage can also be explained by a filling of traps as proposed by Olthof et al 10 They showed that doping at ultralow concentrations fill traps in the n-type semiconductor C 60 reducing the threshold voltage in these devices while keeping the ON/OFF ratio of the transistor10. Similarly, Naab et al 19 showed that filling of traps in TIPS-pentacene by an n-dopant facilitates a high electron mobility in TIPS-pentacene (6,13-Bis(triisopropylsilylethynyl)pentacene).…”

Section: Resultsmentioning

confidence: 99%

Doped organic transistors operating in the inversion and depletion regime

et al. 2013

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The inversion field-effect transistor is the basic device of modern microelectronics and is nowadays used more than a billion times on every state-of-the-art computer chip. In the future, this rigid technology will be complemented by flexible electronics produced at extremely low cost. Organic field-effect transistors have the potential to be the basic device for flexible electronics, but still need much improvement. In particular, despite more than 20 years of research, organic inversion mode transistors have not been reported so far. Here we discuss the first realization of organic inversion transistors and the optimization of organic depletion transistors by our organic doping technology. We show that the transistor parameters—in particular, the threshold voltage and the ON/OFF ratio—can be controlled by the doping concentration and the thickness of the transistor channel. Injection of minority carriers into the doped transistor channel is achieved by doped contacts, which allows forming an inversion layer.

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Section: Resultsmentioning

confidence: 99%

Doped organic transistors operating in the inversion and depletion regime

et al. 2013

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“…Notably, trap filling may be advantageous for OTFT applications where a conductive film is not desired and where trap filling by a dopant has been shown to enhance mobilities and permit control over the threshold voltage. 31–34 This attribute of DMBI dopants was exploited in another work, where it was found that TIPS-pentacene can be doped with o -MeO-DMBI to obtain high-mobility n-channel transistors without increasing the bulk conductivity, as is commonly observed when doping organic transistors. 35 …”

Section: Discussionmentioning

confidence: 96%

Mechanistic Study on the Solution-Phase n-Doping of 1,3-Dimethyl-2-aryl-2,3-dihydro-1H-benzoimidazole Derivatives

et al. 2013

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The discovery of air-stable n-dopants for organic semiconductor materials has been hindered by the necessity of high-energy HOMOs and the air sensitivity of compounds that satisfy this requirement. One strategy for circumventing this problem is to utilize stable precursor molecules that form the active doping complex in situ during the doping process or in a postdeposition thermal- or photo-activation step. Some of us have reported on the use of 1H-benzimidazole (DMBI) and benzimidazolium (DMBI-I) salts as solution- and vacuum-processable n-type dopant precursors, respectively. It was initially suggested that DMBI dopants function as single-electron radical donors wherein the active doping species, the imidazoline radical, is generated in a postdeposition thermal annealing step. Herein we report the results of extensive mechanistic studies on DMBI-doped fullerenes, the results of which suggest a more complicated doping mechanism is operative. Specifically, a reaction between the dopant and host that begins with either hydride or hydrogen atom transfer and which ultimately leads to the formation of host radical anions is responsible for the doping effect. The results of this research will be useful for identifying applications of current organic n-doping technology and will drive the design of next-generation n-type dopants that are air stable and capable of doping low-electron-affinity host materials in organic devices.

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“…For example, the integer charge transfer model proposed that electron/hole transfer induced polaron states should govern the ELA, and especially control the Fermi level pinning while the substrate work function is higher (or lower) than the ionization potential (or electron affinity (EA)) of organic films [13]. On the other hand, it was pointed out that band-gap states induced by structure defects [14,15] and impurities [16,17] control the Fermi level position in the energy gap of organic films, i.e., the Fermi level will be quasi-pinned at the position near the HOMO if the EA/work function of the substrate is greater than the ionization potential (IP)/work function of the organic film [18,19].…”

Section: Introductionmentioning

confidence: 98%