Researchers at UC Berkeley have broken another record of photovoltaic efficiency, which could lead to the development of an ultra-light engine that could power drones for days. For the past 15 years, there was 23 percent efficiency in converting heat into electricity with the help of thermovoltaics, but more insight allowed the efficiency to raise to 29 percent. Researchers now aim to reach close to 50 percent efficiency in the near future by applying scientific concepts. The report has been published in Proceedings of the National Academy of Sciences.
This could be a breakthrough for technologies that rely on heavy batteries for power. Thermophotovoltaics are an alternate power source which could help power drones and other unmanned vehicles to operate continuously for days. It could also be used for powering deep space probes for several centuries and ultimately power a house with the help of a generator of an envelope’s size.
The thermophotovoltaics are compact and efficient for a wide range of application with as little as 100 watts to 100 megawatts, having the ability to deliver electricity to 36,000 homes.
Eli Yablonovitch, professor of electrical engineering and computer science (EECS) and corresponding author on the paper said that this project builds upon the work which found key to boosting the solar efficiency by not absorbing more photons but by emitting them by adding a mirror at the back of the photovoltaic cell which broke the efficiency record. The mirror creates a dense infrared luminescent photon gas with the solar cells which later adds voltage.
The team believes that the mirror could serve a double purpose as it first solves one of the biggest problems in thermophotovoltaics which is to exploit the thermal photons with too little energy to produce electricity. The mirror can be used to reflect the small photons to reheat the thermal source which creates another chance for the creation of high energy photon to create and generate electricity. They have achieved this record-breaking result simply by adding a gold mirror and now they are planning to add a dielectric layer above the gold which could improve the efficiency level to close to 36 percent as claimed by Luis M. Pazos Outόn, a postdoctoral researcher in EECS and also a lead author of the paper.
There was 36 percent result just by increasing reflectivity, making other tweaks to the cell using proven scientific techniques, we can reach our target of 50 percent efficiency said Zunaid Omair, a graduate student researcher in EECS. Before their project, the efficiency which was stalled at 23 percent was increased to 29 percent which is really a big deal.
Journal Reference: Proceedings of the National Academy of Sciences.