The National Renewable Energy Laboratory (NREL) of the U.S. has recently developed an improved process of epitaxy which can potentially increase the production speeds of GaAs by 20 times. This may help to cut the costs of III-V PV cells to US$0.2-0.8/watt.
Thanks to their generally outstanding photoelectric property, the III-V compound semiconductors are generally quite ideal for LEDs, communications, and PV power. An example of this is the use of GaAs for PV cells, which can boost the overall conversion rate of the cells to 43%. As of now, the application of the III-V PV cells is still limited to niche areas, such as satellites and drones, due to their high costs and difficult processes.
To improve the generally time-consuming problem of MOVPE, which is the mainstream process for PV cells now, the scientists of NREL have developed a new process, dubbed D-HVPE, which can boost the GaAs semiconductor layer at 320 microns an hour. This is approximately 20 times faster than MOVPE. HVPE, which is an earlier-generation technology, was officially replaced by MOVPE in the 1970s.
With their successful employment of the new D-HVPE process, the research team at NREL was able to successfully produce PV cells that feature a conversion rate topping 25%. In the future, these PV cells are expected to feature a conversion rate of as high as 27%, which is close to the 29% conversion rate of the MOVPE PV cells.
Kelsey Horowitz, a scientist at the Strategic Energy Analysis Center (SEAC) of NREL, points out that the production cost of III-V PV cells will eventually drop to around US$0.2-0.8/watt following their optimization and mass production.
The research result of the NREL team has been published in “Nature Communications.”