Effects of polarization on the band-structure of delafossite transparent conductive oxides

TL;DR

This study employs advanced theoretical methods to analyze the electronic band structures of delafossite transparent conductive oxides, revealing significant insights into their band gaps, defect states, and the limitations of common approximation techniques.

Contribution

It demonstrates that self-consistent GW calculations yield wider band gaps and better agreement with experiments, challenging the use of scissor operators and highlighting the role of defects.

Findings

Self-consistent GW produces wider band gaps than other methods.

Polaronic effects improve agreement with experimental data.

K-dependent modifications question the use of scissor operators.

Abstract

We use hybrid functionals and restricted self-consistent GW, state-of-the-art theoretical approaches for quasiparticle band structures, to study the electronic states of delafossite Cu(Al,In)O$_2$, the first p-type and bipolar transparent conductive oxides. We show that self-consistent GW gives remarkably wider band gaps than all the other approaches used so far. Accounting for polaronic effects in the GW scheme we recover a very nice agreement with experiments. Furthermore, the modifications with respect to the Kohn-Sham bands are strongly k-dependent, which makes questionable the common practice of using a scissor operator. Finally, our results support the view that the low energy structures found in optical experiments, and initially attributed to an indirect transition, are due to intrinsic defects in the samples.