A new barium zirconium sulfide (BaZrS3) thin film, developed by a team at the University at Buffalo, combines strong light absorption with good charge transport — two qualities that could be useful for optoelectronics applications such as photovoltaics, photodetectors, and LEDs. The researchers made the BaZrS3 films by using a laser to heat up and vaporize barium zirconium oxide. The vapor was deposited on a sapphire surface, forming a film, and then converted into the final material through a chemical reaction called sulfurization. A barium zirconium sulfide thin film created by the research team. Courtesy of Douglas Levere/University at Buffalo. BaZrS3 belongs to a category of materials known as chalcogenide perovskites. Chalcogenide perovskites share some features with halide perovskites, but “do not suffer from the toxicity and instability of the latter materials,” researcher Haolei Hui said. These nontoxic, earth-abundant compounds have been produced for decades in powder form. “Now that we have a thin film made from BaZrS3, we can study its fundamental properties and how it might be used in solar panels, LEDs, optical sensors, and other applications,” researcher Xiucheng Wei said. UB physics Ph.D. students Xiucheng Wei (l) and Haolei Hui (r) were the first authors of a new study that reports on the creation of barium zirconium sulfide thin films. The research was led by UB physics professor Hao Zeng. Courtesy of Douglas Levere/University at Buffalo. In solar panels, for example, experimental results suggest that BaZrS3 films would be more efficient at converting sunlight into electricity than traditional silicon-based materials with identical thicknesses, said professor Hao Zeng, who led the research. The new films performed well even when they had imperfections. (Manufacturing nearly flawless materials is typically more expensive.) The absorption coefficient for the thin film was greater than 105 cm−1 at photon energy of greater than 1.97 eV. The films are n-type with carrier mobility greater than 10 cm2/Vs. “For many decades, there have been only a handful of semiconductor materials that have been used, with silicon being the dominant material,” Zeng said. “Our thin films open the door to a new direction in semiconductor research. There’s a chance to explore the potential of a whole new class of materials.” The research was published in Nano Energy (www.doi.org/10.1016/j.nanoen.2019.104317).
