CLEMENT CARLOS ENRICO COB

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mpecec@nus.edu.sg


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2017 - 201912020 - 20212
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    A study of dip-coatable, high-capacitance ion gel dielectrics for 3D EWOD device fabrication
    (MDPI AG, 2017) Clement, C.E; Jiang, D; Thio, S.K; Park, S.-Y; MECHANICAL ENGINEERING
    We present a dip-coatable, high-capacitance ion gel dielectric for scalable fabrication of three-dimensional (3D) electrowetting-on-dielectric (EWOD) devices such as an n × n liquid prism array. Due to the formation of a nanometer-thick electric double layer (EDL) capacitor, an ion gel dielectric offers two to three orders higher specific capacitance (c ? 10 ?F/cm2) than that of conventional dielectrics such as SiO2. However, the previous spin-coating method used for gel layer deposition poses several issues for 3D EWOD device fabrication, particularly when assembling multiple modules. Not only does the spin-coating process require multiple repetitions per module, but the ion gel layer also comes in risks of damage or contamination due to handling errors caused during assembly. In addition, it was observed that the chemical formulation previously used for the spin-coating method causes the surface defects on the dip-coated gel layers and thus leads to poor EWOD performance. In this paper, we alternatively propose a dip-coating method with modified gel solutions to obtain defect-free, functional ion gel layers without the issues arising from the spin-coating method for 3D device fabrication. A dip-coating approach offers a single-step coating solution with the benefits of simplicity, scalability, and high throughput for deposition of high-capacitance gel layers on non-planar EWOD devices. An ion gel solution was prepared by combining the [EMIM][TFSI] ionic liquid and the [P(VDF-HFP)] copolymer at various wt % ratios in acetone solvent. Experimental studies were conducted to fully understand the effects of chemical composition ratios in the gel solution and how varying thicknesses of ion gel and Teflon layers affects EWOD performance. The effectiveness and potentiality of dip-coatable gel layers for 3D EWOD devices have been demonstrated through fabricating 5 1 arrayed liquid prisms using a single-step dip-coating method. Each prism module has been individually controlled to achieve spatial beam steering without the need for bulky mechanical moving parts. © 2017 by the authors.
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    Publication
    Illumination Dependence of Reverse Leakage Current in Silicon Solar Cells
    (Institute of Electrical and Electronics Engineers (IEEE), 2021) Clement, Carlos Enrico; Singh, Jai Prakash; Birgersson, Erik; Wang, Yan; Khoo, Yong Sheng; Mui Koon Tan; SOLAR ENERGY RESEARCH INST OF S'PORE; MECHANICAL ENGINEERING
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    Publication
    Design of shading‐ and hotspot‐resistant shingled modules
    (Wiley, 2021-12-01) Clement, Carlos Enrico; Singh, Jai Prakash; Khoo, Yong Sheng; Halm, Andreas; Tune, Daniel; Birgersson, Erik; Mui Koon Tan; CHEMICAL & BIOMOLECULAR ENGINEERING
    The shingled module has become an attractive interconnection architecture for its higher packing density and superior power generation. However, with longer string lengths and smaller cell areas, these modules are particularly susceptible to developing hotspots from shading elements. In this paper, a framework for the design of hotspot- and shading-resistant shingled modules is presented. An electrothermal model is developed and validated extensively through specially fabricated shingled modules that allow for string-level measurement and analysis. To investigate the relative influence of cell electrical characteristics on power loss and hotspot temperature, we perform a stochastic Monte Carlo simulation which reveals a greater sensitivity to parameters associated with the shaded cell's leakage current. A further study on cells with illumination-dependent Jleakage shows the detriment of this light-induced effect where higher hotspot temperatures can develop. Module-level parameters are also investigated where string length, number of parallel strings, and cell fraction are studied in relation to their impact on module power and hotspot response. Finally, these findings are condensed into a design matrix which defines the space in which module manufacturers may configure shingled modules such that hotspots will not exceed a set threshold temperature.