Performance of lyotropic liquid crystal-based photoelectrochemical capacitors for solar-to- electrical energy conversion

Halls, Jonathan E; Ward, Haydn J; Althali, Amal A; Testut, Laetitia; Kocsis, Dávid; Alhassan, Huda S; Kelly, S M; Lawrence, Nathan S; Wadhawan, Jay D

Abstract

Regenerative photoelectrochemical capacitors, adapted from a experimental system previously reported (J. E. Halls, J. D. Wadhawan, Energy Environ. Sci., 2012, 5, 6541) and based on the doping of a lamellar lyotropic liquid crystal with visible light sensitizer tris(2,2'-bipyridyl)ruthenium(II), N-methylphenothiazine, zinc(II) ions and potassium chloride (as electrolyte) are examined in this work. The two dye species, by virtue of similarity in redox potentials and difference in size and lipophilicity, allow for electron transfer cascades to occur under illumination, which can be harnessed in a power-generating device through the use of a sacrificial counter electrode. In operation as a solar cell, a maximum light-to-electrical power conversion efficiency is reported as being ~5.0% under green light (530 nm centreband, 30 nm bandwidth, 2.2 mW cm-2 intensity), which extrapolates to the opportunistic value of 1% under one Sun conditions. The electrical characteristics of the devices under illumination afford specific capacitances of ca. 0.5-1.0 F g-1 and have fill factors ~20% which are close to the 25% expected for a perfect photogalvanic cell. The time constants of the reported devices (~1.5 s) are consistent with the notion of electroporation of the surfactant lamellae. The advantages of these mid-ranging photoelectrochemical capacitors are suggested as being their low cost and versatility afforded by their flexible liquid framework that appears to realign itself under conditions of open circuit.

Citation

Halls, J. E., Ward, H. J., Althali, A. A., Testut, L., Kocsis, D., Alhassan, H. S., Kelly, S. M., Lawrence, N. S., & Wadhawan, J. D. (2018, November). Performance of lyotropic liquid crystal-based photoelectrochemical capacitors for solar-to- electrical energy conversion. Presented at Sustainable industrial processing summit and exhibition, Rio de Janeiro, Brazil

• Presentation Conference Type: Conference Paper (published)
• Conference Name: Sustainable industrial processing summit and exhibition
• Start Date: Nov 4, 2018
• End Date: Nov 7, 2018
• Acceptance Date: Oct 9, 2018
• Online Publication Date: Oct 9, 2018
• Publication Date: 2018
• Deposit Date: Dec 29, 2018
• Publicly Available Date: Jan 3, 2019
• Journal: SUSTAINABLE INDUSTRIAL PROCESSING SUMMIT AND EXHIBITION Intl. Symp. On… Edited
• Volume: 1
• Pages: 121-130
• Series Title: Metals and materials processing in a clean environment series
• Series ISSN: 2291-1227
• Book Title: Sustainable Industrial Processing Summit SIPS2018 Volume 2. Amatore Intl. Symp. / on Electrochemistry for Sustainable Development
• ISBN: 978-1-987820-84-3
• Keywords: Photogalvanic device; Electrochemical capacitor; Regenerative solar cell; Lyotropic liquid crystals; Molecular electrochemistry; Photoelectrochemistry
• Public URL: https://hull-repository.worktribe.com/output/1199426
• Publisher URL: https://www.flogen.org/sips2018/paper-2-410.html
• Contract Date: Dec 29, 2018