Supporting Information
Solution Processable Electrochemiluminescent Ion Gels for Flexible, Low Voltage, Emissive Displays on Plastic
Hong Chul Moon†, Timothy P. Lodge,†,‡,* and C. Daniel Frisbie†,*
†
Department of Chemical Engineering & Materials Science
University of Minnesota, 421 Washington Ave. SE, Minneapolis, Minnesota 55455, USA ‡
Department of Chemistry, University of Minnesota, 207 Pleasant Street SE, Minneapolis, Minnesota 55455, USA
* Corresponding authors. E-mail:
[email protected] (T.P.L),
[email protected] (C.D.F)
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S1. Demonstration of brush-painted silver as a top electrode for ECL devices To demonstrate the possibility of using brush-painted silver as a top electrode, we fabricated an ECL device in which the silver electrode was drawn using a brush on the top of the ECL gel on patterned ITO-coated glass. Because the silver electrode should be continuous, we drew connected silver lines with the letters ‘ECL’ (Figure S1). When we applied a VPP of 3.6 V at a frequency of 60 Hz, the ECL device turned ON following the drawn silver electrode. This result demonstrates that brush-painted silver is suitable for ECL devices as a top electrode.
Figure S1. Photographs of the ECL device utilizing a brush-painted silver electrode consisting of lines and letters of ‘ECL’ (a) as fabricated and (b) in the ON state at a frequency of 60 Hz and a VPP of 3.6 V (−1.8 V ~ +1.8 V) where the image was reflected along the vertical axis for easy comparison between Figures S1a and 1b.
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S2. Transient profiles at different frequencies for Ru(bpy)32+-containing ECL devices We recorded transient profiles at different frequencies. For both higher (120 Hz) or lower (30 Hz) than 60 Hz, all the transient profiles of applied voltage, current and ECL intensity showed similar behavior, with the exception of the signal period (due to using a different frequency) and the response time (shorter response time at higher frequency).
Figure S2. Transient profiles of applied voltage (VPP = 3.6 V, square wave) (black), current (red) and ECL intensity (blue) for ECL devices at a certain time under different frequency (a) 30 Hz and (b) 120 Hz. S3
S3. Cyclic Voltammograms for Ru(bpy)3Cl2 and Ir(diFppy)2(bpy)PF6 Cyclic voltammetry experiments for Ru(bpy)3Cl2 and Ir(diFppy)2(bpy)PF6 were performed to determine the potentials where redox reaction occured (Figure S3). Since Ir(diFppy)2(bpy)PF6 has a higher oxidation potential (+1.23 V) and a lower reduction potential (–1.34 V) than Ru(bpy)3Cl2 (oxidation and reduction at +0.91 V and –1.24 V, respectively), a slightly larger turn-ON voltage is required for Ir(diFppy)2(bpy)PF6-containing ECL device.
Figure S3. Cyclic voltammograms for Ru(bpy)3Cl2 (red) and Ir(diFppy)2(bpy)PF6 (green) used in this study, in which solvent was acetonitrile and 0.1 M of tetrabutylammonium perchlorate was employed as a supporting electrolyte. Working and counter electrodes were Pt, and silver wire was employed as a reference electrode with an internal standard (ferrocene). Scan rate was 75 mV/s. It is noted that the irreversible oxidation peak of ~ +0.62 V for Ru(bpy)3Cl2 corresponds to oxidation of chloride ions.1
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S4. UV-Vis spectrum (absorption) of Ru(bpy)3Cl2 and ECL spectrum (emission) of Ir(diFppy)2(bpy)PF6 Absorption spectrum of Ru(bpy)3Cl2 (red) and emission spectrum of Ir(diFppy)2(bpy)PF6 (blue) were recorded as given in Figure S4. The emission of Ir(diFppy)2(bpy)PF6 by ECL overlaps only slightly with the absorption of Ru(bpy)3Cl2. Therefore, the contribution of resonance energy transfer to the enhancement of red-orange colored light in a mixed luminophore system should be very small.
Figure S4. UV-Vis spectrum (absorption) spectrum of Ru(bpy)3Cl2 (red) and ECL spectrum (emission) of Ir(diFppy)2(bpy)PF6 (blue)
References and Notes (1) Tokel, N. E.; Bard, A. J. J. Am. Chem. Soc. 1972, 94, 2862.
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