Halide perovskites exhibit remarkable properties as solar-cell absorbers, featuring both direct bandgaps suitable for sunlight absorption and long-lived charge carriers beneficial for charge extraction. However, the intrinsic instabilities and high toxicity of these water-soluble lead salts may impede the commercialization of this technology. Notably, even the origin of the materials' superior photophysical properties remains unclear, underscoring the importance of synthesizing and studying functional analogs of the lead perovskites. However, most stable materials studied as analogs have displayed weak sunlight absorption and short carrier lifetimes.<br/><br/>We recently introduced halide double perovskites, which can accommodate a much greater range of metals, as solar absorbers. Armed with this substitutional flexibility, we have explored alternative metals that can be incorporated into the perovskite lattice. Studying the electronic differences between the lead perovskites and lead-free double perovskites has shown us how to synthetically tune double perovskites to better absorb sunlight. I will share our understanding of how to manipulate the symmetry and energy of the bandgap transition in these materials through i) dilute impurity alloying, ii) stoichiometric metal substitution, and iii) dimensional reduction. Our studies have led us to double perovskites with very similar properties to the lead perovskites, allowing us to articulate design rules for perovskite solar absorbers.  <br/>

Teaching halide double perovskites to absorb sunlight

2019 Spring National Meeting

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