Predicting atomic interface behavior from first principles

The atomic structure at the interface of two materials helps determine a device’s properties and performance. However, these atomic structures are mostly only known for simple interfaces in which both materials have similar crystal structure and match easily. More complex interfaces must be explored with experiments that are time consuming if not outright impossible.

Sharan et al. extended methods used to predict bulk crystal structure to predict the atomic structures, and resulting properties and performance, of complex interface systems.

“Our work pioneers predicting complex interfaces between dissimilar materials from first principles,” said author Stephan Lany. “An ability to predict complex interface structures and calculate properties before they are made will aid the understanding and development of new applications and devices.”

The authors applied their approach to the interface of tin(IV) oxide (SnO₂) and cadmium telluride (CdTe), a heterojunction of interest to photovoltaic device manufacturers. This interface is typically processed with cadmium chloride (CdCl₂) because this treatment is known to improve the performance of CdTe-based photovoltaics, but the underlying mechanism is not well understood.

Their simulations showed treating this interface with CdCl₂ causes an atomically thin CdCl₂ interlayer to form. Modeling electronic properties and device efficiencies revealed that the interlayer markedly improves the photovoltaic performance by building a bridge for electrons across structurally dissimilar materials.

These results demonstrate how a two-dimensional interlayer allows two otherwise incompatible materials to match at an interface, which could create new opportunities in materials design. Next, the authors would like to use this method to identify other interlayer phases that can improve non-ideal interface systems.

Source: “Atomically thin interlayer phase from first principles enables defect-free incommensurate SnO₂/CdTe interface,” by Abhishek Sharan, Marco Nardone, Dmitry Krasikov, Nirpendra Singh, and Stephan Lany, Applied Physics Reviews (2022). The article can be accessed at https://doi.org/10.1063/5.0104008 .