Towards predictive band gaps for halide perovskites: Lessons from one-shot and eigenvalue self-consistent GW

Journal Article · Thu Oct 17 00:00:00 EDT 2019 · Physical Review Materials

DOI:https://doi.org/10.1103/physrevmaterials.3.103803· OSTI ID:1676369

Leppert, Linn  ^[1]; Rangel, Tonatiuh ^[2]; Neaton, Jeffrey B. ^[3]

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1. Univ. of Bayreuth (Germany)
2. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Foundry
3. Univ. of California, Berkeley, CA (United States); Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). Molecular Foundry; Kavli Energy NanoScience Institute, Berkeley, CA (United States)

Halide perovskites constitute a chemically diverse class of crystals with great promise as photovoltaic absorber materials, featuring band gaps between about 1 and 3.5 eV depending on composition. Their diversity calls for a general computational approach to predicting their band gaps. However, such an approach is still lacking. Here, we use density functional theory (DFT) and ab initio many-body perturbation theory within the $\mathit{GW}$ approximation to compute the quasiparticle or fundamental band gap of a set of ten representative halide perovskites: ${\mathrm{CH}}_3{\mathrm{NH}}_3{\mathrm{PbI}}_3$ ( ${\mathrm{MAPbI}}_3$), ${\mathrm{MAPbBr}}_3,{\mathrm{CsSnBr}}_3$, ( ${\mathrm{MA})}_2{\mathrm{BiTlBr}}_6,{\mathrm{Cs}}_2{\mathrm{TlAgBr}}_6,{\mathrm{Cs}}_2{\mathrm{TlAgCl}}_6,{\mathrm{Cs}}_2{\mathrm{BiAgBr}}_6,{\mathrm{Cs}}_2{\mathrm{InAgCl}}_6,{\mathrm{Cs}}_2{\mathrm{SnBr}}_6$, and ${\mathrm{Cs}}_2{\mathrm{Au}}_2{\mathrm{I}}_6$. Comparing with recent measurements, we find that a standard generalized gradient exchange-correlation functional can significantly underestimate the experimental band gaps of these perovskites, particularly in cases with strong spin-orbit coupling (SOC) and highly dispersive band edges, to a degree that varies with composition. We show that these nonsystematic errors are inherited by one-shot $G_0{W}_0$ and eigenvalue self-consistent ${\mathrm{GW}}_0$ calculations, demonstrating that semilocal DFT starting points are insufficient for ${\mathrm{MAPbI}}_3,{\mathrm{MAPbBr}}_3,{\mathrm{CsSnBr}}_3$, ( ${\mathrm{MA})}_2{\mathrm{BiTlBr}}_6,{\mathrm{Cs}}_2{\mathrm{TlAgBr}}_6$, and ${\mathrm{Cs}}_2{\mathrm{TlAgCl}}_6$. On the other hand, we find that DFT with hybrid functionals leads to an improved starting point and ${GW}_0$ results in better agreement with experiment for these perovskites. Our results suggest that ${GW}_0$ with hybrid functional-based starting points are promising for predicting band gaps of systems with large SOC and dispersive bands in this technologically important class of semiconducting crystals.</

• Research Organization: Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States)
• Sponsoring Organization: USDOE Office of Science (SC), Basic Energy Sciences (BES); National Science Foundation (NSF); German Research Foundation (DFG)
• Grant/Contract Number: AC02-05CH11231; DMR-1708892; SFB840
• OSTI ID: 1676369
• Journal Information: Physical Review Materials, Vol. 3, Issue 10; ISSN 2475-9953
• Publisher: American Physical Society (APS)
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
Band gap
electronic structure
energy materials
perovskite
density functional theory
GW method