Soft Nondamaging Contacts Formed from Eutectic Ga-In for the Accurate Determination of Dielectric Constants of Organic Materials

Evgenia Douvogianni; Xinkai Qiu; Li Qiu; Fatemeh Jahani; Floris B Kooistra; Jan C Hummelen; Ryan C Chiechi

doi:10.1021/acs.chemmater.8b02212

Soft Nondamaging Contacts Formed from Eutectic Ga-In for the Accurate Determination of Dielectric Constants of Organic Materials

Chem Mater. 2018 Aug 28;30(16):5527-5533. doi: 10.1021/acs.chemmater.8b02212. Epub 2018 Aug 3.

Authors

Evgenia Douvogianni^{1

2}, Xinkai Qiu^{1

2}, Li Qiu^{1

2}, Fatemeh Jahani^{1

2}, Floris B Kooistra^{1

2}, Jan C Hummelen^{1

2}, Ryan C Chiechi^{1

2}

Affiliations

¹ Stratingh Institute for Chemistry, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands.
² Zernike Institute for Advanced Materials, Nijenborgh 4, 9747 AG Groningen, The Netherlands.

Abstract

A method for accurately measuring the relative dielectric constant (ε_r) of thin films of soft, organic materials is described. The effects of the bombardment of these materials with hot Al atoms, the most commonly used top electrode, are mitigated by using electrodes fabricated from eutectic gallium-indium (EGaIn). The geometry of the electrode is defined by injection into microchannels to form stable structures that are nondamaging and that conform to the topology of the organic thin film. The ε_r of a series of references and new organic materials, polymers, and fullerene derivatives was derived from impedance spectroscopy measurements for both Al and EGaIn electrodes showing the specific limitations of Al with soft, organic materials and overcoming them with EGaIn to determine their dielectric properties and provide realistic values of ε_r.