Defect tolerance (DT) is the resilience of electronic transport properties to the presence of defects in semiconductors. The tolerance to defects is a consequence of the fact that defects in these materials introduce only shallow defect levels. Recently, DT has garnered considerable interest due to the rise of hybrid perovskites as PV absorbers. However, concerns surrounding toxicity as well as long-term stability has motivated a search for "perovskite-inspired'' materials. So far, the presence of partially-oxidized cations has been the guiding design principle for identifying and discovering defect-tolerant semiconductors. However, our recent work on binary and pseudo-binary semiconductors has identified additional structural and chemical features that promote DT. We confirmed that the presence of partially-oxidized cations promote shallow cation vacancies. However, key structural features are needed to promote shallow anion vacancies. Specifically, we identified two classes of structures that promote shallow anion vacancies, including the CsCl-type structure and structures with low anion coordination. Ternary semiconductors are more complicated, both in terms of their structures and bonding chemistry. At the same time, they also offer more opportunities for chemical and structural tunability. We have extend our understanding of DT to ternary semiconductors through extensive first-principles defect calculations. Our preliminary results suggest that there may be additional factors that need to be considered, for example, the specific orbital compositions of the band edges.

Key structural and chemical features of defect-tolerant semiconductors

2019 Fall National Meeting

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