Flexible Solar Panels, Printed on Inkjet Printers, Prove Their Worth for Powering Novel Projects
Designed to easily scale up, KAUST's new inkjet-printed solar panels are more efficient than any of their predecessors.
Researchers at the King Abdullah University of Science and Technology (KAUST) have showcased a new way of printing organic solar cells from an inkjet printer, creating thin and light flexible panels capable of resting atop a soap bubble.
"The tremendous developments in electronic skin for robots, sensors for flying devices and biosensors to detect illness are all limited in terms of energy sources," explains Dr. Eloïse Bihar, lead researcher, of the team's work. "Rather than bulky batteries or a connection to an electrical grid, we thought of using lightweight, ultra-thin organic solar cells to harvest energy from light, whether indoors or outdoors."
Traditional ultra-thin solar cells can be manufactured in a variety of ways, all of which have their own drawback — in particular the common indium tin oxide (ITO) panels being brittle and inflexible, meaning it's difficult to confirm the cells to an object's shape. The KAUST team's solution: Creating "inks" for each of the layers in the solar cell, and printing them using an inkjet printer.
Inkjet printing is a well-proven technology and scales well, though the formulation of the inks for compatibility with inkjet printers was a challenge. "Inkjet printing is a science on its own," notes PhD student Daniel Corzo. "The intermolecular forces within the cartridge and the ink need to be overcome to eject very fine droplets from the very small nozzle. Solvents also play an important role once the ink is deposited because the drying behavior affects the film quality."
The finished cells, formed of a flexible polymer known as PEDOT:PSS, showed a power conversion efficiency (PCE) of 4.73 percent — an uplift over the previous-best fully-printed cell, which achieved 4.1 percent PCE. The team also showed that the material can be printed onto a flexible substrate, as swell as onto glass, though this did prove to drop the PCE to 3.6 percent.
"Our findings mark a stepping-stone for a new generation of versatile, ultra-lightweight printed solar cells," claims Bihar, "that can be used as a power source or be integrated into skin-based or implantable medical devices."
The team's work has been published under closed-access terms in the journal Advanced Materials Technologies.
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