The supercapacitors can be used in various devices, including streetlights and self-powered electronic devices such as sensors, Bengaluru-based IISc said in a press release.
Bengaluru: Researchers at the Department of Instrumentation and Applied Physics (IAP), Indian Institute of Science (IISc), and collaborators have designed a new supercapacitor that can be charged by shining light on it.
The supercapacitors can be used in various devices, including streetlights and self-powered electronic devices such as sensors, Bengaluru-based IISc said in a press release.
“Capacitors are electrostatic devices that store energy as charges on two metal plates called electrodes. Supercapacitors are upgraded versions of capacitors – they exploit electrochemical phenomena to store more energy,” Abha Misra, Professor at IAP and corresponding author of the study published in the ‘Journal of Materials Chemistry A”, was quoted as saying in the release.
The electrodes of the new supercapacitor were made of Zinc Oxide (ZnO) nanorods grown directly on Fluorine-doped Tin Oxide (FTO), which is transparent. It was synthesised by Pankaj Singh Chauhan, first author and CV Raman postdoctoral fellow in Misra’s group at IISc.
Both ZnO and FTO are semiconductors with appropriately aligned energy levels, enabling superior performance of the photo-rechargeable supercapacitor, the release said.
FTO, being transparent, allows light to fall on the optically active ZnO nanorods, which charges the supercapacitor.
The capacity for storing charges (capacitance) is inversely proportional to the distance between the electrodes, it said.
“As the distance becomes very small, the capacitance shoots up,” Misra stated.
“In electrostatic capacitors, maintaining a small distance between electrodes is difficult. However, in a supercapacitor, the electrodes’ charges attract the electrolyte’s oppositely charged ions, resulting in the formation of a charge layer just atoms away from each other – called an electric double layer or EDL. This results in the high capacitance of supercapacitors,” the release stated.
When the researchers shined ultraviolet (UV) light on their supercapacitor, they noticed a huge increase in the capacitance, several times higher than previously reported supercapacitors.