Pillalamarri Srikrishnarka
Dielectica traverses through the literature on this topic – and summarizes as they appear.
Key words: Wearable electronics, Flexible solar cells, TiO2 nanotube
Chennai, India: Whenever we hear about wearable electronics, the most successful and widely accepted technology that reached the masses is in the form of a smartwatch. It is not only showing time, but it is also capable of counting steps, total distance moved, measuring heart rate, body temperature and even conducting ECG of human body. This invention has completely transformed our way of life. The major limitation for such kind of wearable technologies is the power supply, the battery used is limited and needs charging for continued usage. This limits the overall usability of the system. Imagine if we have a smartwatch that doesn’t need any charging!
In this context, extensive research has been conducting and researchers from Fudan University and EMPA were successful in fabricating solar concentrators for fiber solar cells.
So, before directly going to the fabrication procedure and the detail technology inside it, let’s first look into the basics of what is a solar cell and solar concentrator means. A solar cell is a device that converts light energy into electricity and a solar concentrator helps further in improving the solar cell’s efficiency. Sun is our abundant source of energy and thus we need to effectively and efficiently use that energy for powering our daily use electronic gadgets. Solar panels are one of the prime examples for efficient power production, however, the cost of the panels and carry such kind panels during mobility restrict their uses in such purpose. Since, it lacks flexibility, solar panels, can’t be worn on clothes and is limits its further uses. Let’s limit the focus of this article towards mobility alone. In the past, a series of reports which have been addressed for this purpose and researchers have come up with flexible solar cells in this context. The seminal work by Prof. Graetzel of EPFL, Switzerland, who invented the dye-sensitized solar cell totally revolutionized the field of photovoltaics. A dye-sensitized solar cell consists of a photoanode which is made of semiconducting metal oxides typically of tin, zinc and titania. This photoanode is then bleached in a dye, which could be of natural or synthetic origin, is then immersed in an electrolyte solution and finally platinum or carbon is used as the photocathode.
In the current article written by Huang et al., authors initially fabricated a flexible fiber-based dye-sensitized solar cell. [1] Consisting of a titanium wire which was anodized to form flexible titanium dioxide nanotubes (TN). Further, carbon nanotube (CN) fiber was initially fabricated by a technique known as floating catalyst chemical vapor deposition. As a result of this process, the obtained CN fibers intertwined with the TN fibers were achieved and this structure was used as photoanode of the device. This composite fiber-wire is then immersed in N719 dye and the electrolyte and cell has been fabricated by making a sandwich structure with the photoanode and photocathode. Finally, a methacryloxypropyl- terminated polydimethylsiloxane with a UV-initiator along with a fluorescent dye known Comarin 6 was used as a solar concentrator. Multiple flexible solar cells were taken and the above solution was poured on these fibers and a film was made. Upon drying, the film was tested under a solar simulator and the researcher observed an enhancement of 84 % in the conversion efficiency and taking the device efficiency to ~7.89 %. With multiple flexible solar cell fibers with a 3 cm2 area of the solar concentrator, they have obtained a power output of 0.89 mW, which is substantial to energize the smart watch.
References:
[1] Chieh-Szu Huang et al. J. Mater. Chem. A, 2021, DOI: https://doi.org/10.1039/D1TA04984D (Just accepted)