The essential catalyst for the process is tungsten diselenide. The abundance of tungsten in the Earth’s crust is thought to be about 1.5 parts per million. It is one of the more rare elements and most of it is mined in China, Russia, and Portugal. The United States has no tungsten mines.
The above tells me that these scientists are trolling for government grants for a solar cell scheme that is limited by the cost and availability of tungsten.