Electronic functionalization of solid-to-liquid interfaces between organic semiconductors and ionic liquids: Realization of very high performance organic single-crystal transistors

Abstract

High-performance electronic function of current amplification is realized with the use of solid-to-liquid interfaces between organic semiconductors and ionic liquid. To hold in place the ionic liquid of 1-ethyl-3-methyl-imidazolium bis(trifluoromethanesulfonyl)imide known for low viscosity and high ionic conductivity, an elastomeric well structure is fabricated with polydimethylsiloxane on which organic single crystals of rubrene are electrostatically attached. As the result of rapid formation of electric double layers in the ionic liquid interfacing, the high-mobility organic semiconductor crystals’ fast-switching transistor function is demonstrated with the application of gate voltage, realizing the highest sheet transconductance, namely, amplifying performance, ever achieved.

Organic field-effect transistors using single crystals

“…Since σ T ϒ is the product of mobility and the capacitance of the device, both parameters should be large to have the best sheet transconductance. σ T ϒ is as high as 20 µS when V D = −1 V, which is the best performance among all reported OFETs [50].…”

Nanoscale Conducting Channels at the Surface of Organic Semiconductors Formed by Decoration of Molecular Steps with Self‐Assembled Molecules

“…It has been shown that molecular steps and grain boundaries lead to trapping and scattering of charge carriers that lower mobility in OFETs, [27,28] especially in the regime of high carrier density realized in ionic-liquid gated OFETs and OFETs with high k dielectrics. [29][30][31] Oxygen impurities are also known to influence the charge carrier transport and optical properties of organic semiconductors by forming in-gap trap states. [32][33][34][35][36][37] The impact of these extrinsic scattering and trapping processes can be reduced or eliminated by selectively doping the above-mentioned defects with a SAM, which could result in a better understanding of charge transport in organic semiconductors.…”

High-performance n-type organic field-effect transistors with ionic liquid gates

“…To this end, we have fabricated N , NЉ-bis͑n-alkyl͒-͑1,7 and 1,6͒-dicyanoperylene-3,4:9,10-bis͑dicarboximide͒s ͑PDIF-CN 2 ͒ single-crystal transistors with IL, using the same methods used for p-type rubrene single crystals. 16,17 As organic material we have selected PDIF-CN 2 , 19,20 which exhibits the highest electron mobility reported to date ͑1-6 cm 2 / V s͒. 21 We show that the electron mobility of PDIF-CN 2 single-crystal transistors with IL ͑as high as 5.0 cm 2 / V s in air͒ is comparable to the corresponding devices without IL, thus having air as gate dielectric.…”

“…18 The obtained T reaches values as high as 6.1 S at V D = 0.1 V, two orders of magnitude larger than the best n-type OFETs so far 18 and comparable to the value of the best p-type OFETs with IL gates. 16 The output characteristics of the PDIF-CN 2 single crystal OFETs with ͓P13͔͓TFSI͔ are shown in Fig. 2͑c͒.…”

“…Indeed, for p-type transistors, the operation of high-quality OFETs based on EDL gating has been recently reported by several groups. [8][9][10][11][12][13][14] Among all investigated EDLOFETs, room temperature ionic liquids ͑ILs͒ are particularly promising, [15][16][17][18] as they have shown to enable a very fast response ͑compared to other types of electrolytes͒ to changes in the gate voltage. For p-type transistors ͑based on rubrene͒ it was also recently found that the surface of organic semiconductors is not damaged by the ILs, and mobility values up to 9.5 cm 2 / V s can be achieved by selecting the proper IL.…”