Correlated Metal LaNiO ₃ as a p‐Type Transparent Conductor

ABSTRACT

Transparent Conducting Oxides (TCOs) are essential as electrodes in a broad range of optoelectronic applications. A range of n‐type TCOs meeting application requirements for transparency and conductivity have been developed, whereas efficient and stable p‐type TCOs have so far remained a challenge, limiting the opportunities to explore novel architectures for optoelectronic devices. In particular, a high‐performance p‐type transparent electrode would enable the use of n‐type absorber layers in superstrate solar cells. Recently, correlated metals featuring strong interelectron repulsion have enabled enhanced transparency in highly conducting n‐type systems leading to figures of merit comparable with those of conventional degenerate semiconductors such as ITO. Here we demonstrate that the p‐type correlated metal LaNiO ₃ is a robust and scalable p‐type transparent conductor with excellent performance compared to existing materials. We achieve a Haacke Figure of Merit more than double, and Anand Exact Figure of Merit 1.4 times that of the respective highest performing p‐type TCOs, at thicknesses ≤12 nm. For a free‐standing 3 nm film, we obtained a minimal sheet resistance of 1070 Ω/□ and transmittance of >85%. The films are air stable and show a thickness‐tuneable balance of sheet resistance and transparency which is critical for targeted applications.