KBaTeBiO₆: a lead-free, inorganic double-perovskite semiconductor for photovoltaic applications

Arashdeep Singh Thind, Shalinee Kavadiya, Mojgan Kouhnavard, Robin Wheelus, Sung Beom Cho, Liang-Yi Lin,Clayton Kacica,Hemant Kumar Mulmudi, Kinga A Unocic, Albina Y. Borisevich, Ghanshyam Pilania, Pratim Biswas, Rohan Mishra

Chemistry of Materials (2019)

Solar cells made up of lead-halide perovskites have shown a remarkable increase in power conversion efficiency; however, they are plagued with instability issues that combined with the toxicity of lead have led to a search for new semiconductors made up of heavy and non-toxic metals such as bismuth. Here, we report on a new, inorganic, double perovskite oxide semiconductor: KBaTeBiO6, which has an experimental indirect band gap of 1.88 eV and shows excellent stability. We combined data analytics and high throughput density-functional-theory calculations to search through thousands of hypothetical inorganic double perovskite oxides containing bismuth and predict KBaTeBiO6 as a potential photovoltaic material, which was subsequently synthesized using a wet-chemistry route. The calculated effective mass of the charge carriers for KBaTeBiO6 is comparable to the best performing Bi-halide double perovskites. Our work demonstrates the untapped potential of inorganic Bi-based double perovskite oxides—that offer the ability to change both the cation combination and their stoichiometry to achieve desired electronic properties—as exciting, benign and stable alternatives to lead-halide perovskites for various semiconducting applications.