Development of Graphene Nano-Platelet Ink for High Voltage Flexible Dye Sensitized Solar Cells with Cobalt Complex Electrolytes

Graphene nanoparticles have been subject to intensive investigation as a replacement for platinum as the catalyst in dye sensitized solar cells (DSCs), but few of these investigations examine the application for flexible cells with deposition processes suitable for industrial fabrication. This work introduces a transparent water based graphene ink that can be dried rapidly at less than 110 ºC making it particularly suitable for roll to roll deposition on plastic substrates. This ink has application as a catalyst for dye sensitized solar cells utilizing cobalt complex electrolytes with efficiency of over 6 % and a Voc of 0.89 V at 1 sun demonstrated. A flexible DSC with a printed catalyst and cobalt redox mediator is reported, with efficiency of over 6.0 % and Voc of 0.6 V at 800 lux

Porous Carbon Materials as Supreme Metal-Free Counter Electrode for Dye-Sensitized Solar Cells

Counter electrode (CE), as one of the key components of dye-sensitized solar cells (DSSCs), plays a significant role in the overall efficiency and cost of the device. Platinum metal has long been considered one of the most efficient CEs for DSSCs, but its scarcity, high cost, and low stability in I−/I3− redox couple limit its application in the large scale. In this chapter, we provide a broad overview on porous carbon materials as supreme metal-free counter electrode for DSSCs. In the first part, we concisely discuss on the importance and working principle of DSSCs and then the influence of counter electrode on the photovoltaic performance of DSSCs. Afterward, we review different synthetic methods and precursors of porous carbon materials and their efficiency in DSSCs. In the last section, we discuss in detail with example how to characterize and evaluate the device performance using porous carbon materials as counter electrode. Finally, we finish this chapter with a brief summary and outlook of porous carbon materials as counter electrodes in DSSCs

Inkjet-printed graphene electrodes for dye-sensitized solar cells

We present a stable inkjet printable graphene ink, formulated in isopropyl alcohol via liquid phase exfoliation of chemically pristine graphite with a polymer stabilizer. The rheology and low deposition temperature of the ink allow uniform printing. We use the graphene ink to fabricate counter electrodes (CE) for natural and ruthenium-based dye-sensitized solar cells (DSSCs). The repeatability of the printing process for the CEs is demonstrated through an array of inkjet-printed graphene electrodes, with ∼5% standard deviation in the sheet resistance. As photosensitizers, we investigate natural tropical dye extracts from Pennisetum glaucum, Hibiscus sabdariffa and Caesalpinia pulcherrima. Among the three natural dyes, we find extracts from C. pulcherrima exhibit the best performance, with ∼0.9% conversion efficiency using a printed graphene CE and a comparable ∼1.1% efficiency using a platinum (Pt) CE. When used with N719 dye, the inkjet-printed graphene CE shows a ∼3.0% conversion efficiency, compared to ∼4.4% obtained using Pt CEs. Our results show that inkjet printable graphene inks, without any chemical functionalization, offers a flexible and scalable fabrication route, with a material cost of only ∼2.7% of the equivalent solution processed Pt-based electrodes.Authors acknowledge support from CAPREX, Cambridge Africa Alborada Fund, Carnegie-University of Ghana Next Generation of Africa Academics programme and the Royal Academy of Engineering (RAEng) through a research fellowship (Graphlex)

Polymer/Graphene Nanocomposite: Preparation to Application

Graphene has emerged as a topic of huge scientific interest due to its high surface area, exceptional mechanical properties, electron transfer, and other physical properties. In polymers, this one-atom thick 2D crystal may significantly enhance the physical properties at very small loading level. In this review, essential characteristics of polymer/graphene nanocomposite have been discussed. Moreover, fabrication techniques (in situ method, solution route, melt technique) frequently employed for polymer/graphene nanocomposite have been discussed. Applications of these nanocomposites in Li-ion batteries, electronic devices, and solar cells have been conversed along with the current challenges associated with processing and scalability of these materials

CVD-graphene/graphene flakes dual-films as advanced DSSC counter electrodes

The use of graphene-based electrodes is burgeoning in a wide range of applications, including solar cells, light emitting diodes, touch screens, field-effect transistors, photodetectors, sensors and energy storage systems. The success of such electrodes strongly depends on the implementation of effective production and processing methods for graphene. In this work, we take advantage of two different graphene production methods to design an advanced, conductive oxide- and platinum-free, graphene-based counter electrode for dye-sensitized solar cells (DSSCs). In particular, we exploit the combination of a graphene film, produced by chemical vapor deposition (CVD) (CVD-graphene), with few-layer graphene (FLG) flakes, produced by liquid phase exfoliation. The CVD-graphene is used as charge collector, while the FLG flakes, deposited atop by spray coating, act as catalyst for the reduction of the electrolyte redox couple (i.e., I3-/I-- and Co+2/+3). The as-produced counter electrodes are tested in both I3-/I-- and Co+2/+3-based semitransparent DSSCs, showing power conversion efficiencies of 2.1% and 5.09%, respectively, under 1 SUN illumination. At 0.1 SUN, Co+2/+3-based DSSCs achieve a power conversion efficiency as high as 6.87%. Our results demonstrate that the electrical, optical, chemical and catalytic properties of graphene-based dual films, designed by combining CVD-graphene and FLG flakes, are effective alternatives to FTO/Pt counter electrodes for DSSCs for both outdoor and indoor applications

Transparent graphene-based counter-electrodes for iodide/triiodide mediated dye-sensitized solar cells

A new highly transparent and low cost counter-electrode for dye-sensitized solar cells was fabricated, comprised of a structured graphene film over nickel nanoparticles. Annealed nickel particles induced an enhanced restoration of graphene double bonds, which led to cells with energy conversion efficiencies similar to those using a conventional platinum electrode

Counter electrode materials based on carbon nanotubes for dye-sensitized solar cells

Efficiency, stability, and cost-effectiveness are the prime challenges in research of materials for solar cells. Technologically as well as scientifically, attention gained by dye-sensitized solar cells (DSSCs) stems from their low material and fabrication costs as well as high efficiency projections. The aim of this study is to explore the carbon nanotubes (CNTs) based counter electrode (CE) materials for DSSCs and to reconnoiter the suitable alternative materials in place of noble metals such as Platinum (Pt), and Gold (Au).. Various classes of CE materials based on CNTs including pure single walled, double walled, and multiwalled CNTs, doped CNTs and their hybrid composites with various polymers, and transition metal compounds are discussed comprehensively in light of the research work started since the inspection of DSSCs and CNTs.The properties associated with such materials, including surface morphology, structural determination, thermal stability, and electrochemical activity, are also thoroughly analyzed and compared. This work provides a thorough insight into the possibility of exploiting CNTs as alternative CE materials. In addition to the above, this study also includes the working and brief overview of materials for other components of DSSCs such as photoanode, electrolyte, and sensitizer.