China’s Solar Dominance Faces New Rival: An Ultrathin Film

TOKYO—China’s near-monopoly on the solar-energy market has prompted the U.S. and allies to step up the search for workarounds. Engineers believe they have found one in a type of solar cell that looks and feels like camera film.

Japan is pushing the technology with subsidies and other support, a sign of how renewable energy, alongside other high-tech fields such as semiconductors, has become a geopolitical football.