Crystal structure of Cu2Te predicted within adaptive genetic algorithm

Cu₂Te is one of the most commonly used conductive back-contacting materials for high-efficiency CdTe-based solar cells. However, the detailed crystal structure of Cu₂Te is still undetermined blocking property investigations of the Cu₂Te-based solar cell systems. Some models have been proposed but all of them have positive formation energy. We have performed adaptive genetic algorithm crystal structure search to find low energy crystal structures of Cu₂Te. We found a new layered-structure edged by Te atoms with negative formation energy from first-principles calculations within local density approximation. This layered structure consists of tilted Cu₂Te ribbon arrays. Structural and electronic properties of the newly found Cu₂Te structure will be discussed in detail.

Supported in part US DOE, NSF of China, and US NSF.