Atomically thin interlayer phase from first principles enables defect-free incommensurate SnO 2 /CdTe interface

• Published in: Applied physics reviews 2022-12, Vol.9 (4)
• Main Authors: Sharan, Abhishek, Nardone, Marco, Krasikov, Dmitry, Singh, Nirpendra, Lany, Stephan
• Format: Article
• Language: English
• ISSN: 1931-9401; 1931-9401

Advancing optoelectronic and emerging technologies increasingly requires control and design of interfaces between dissimilar materials. However, incommensurate interfaces are notoriously defective and rarely benefit from first-principles predictions, because no explicit atomic-structure models exist. Here, we adopt a bulk crystal structure prediction method to the interface geometry and apply it to SnO 2 /CdTe heterojunctions without and with the addition of CdCl 2 , a ubiquitous and beneficial, but abstruse processing step in CdTe photovoltaics. Whereas the direct SnO 2 /CdTe interface is highly defective, we discover a unique two-dimensional CdCl 2 interphase, unrelated to the respective bulk structure. It facilitates a seamless transition from the rutile to zincblende lattices and removes defect-states from the interface bandgap. Implementing the predicted interface electronic structure in device simulations, we demonstrate the theoretical feasibility of bufferless oxide-CdTe heterojunction solar cells approaching the Shockley–Queisser limit. Our results highlight the broader potential of designing atomically thin interlayers to enable defect-free incommensurate interfaces.