2014/08/25 by Daniel Lüftner, Sivan Refaely-Abramson, Sivan Refaely‐Abramson +5 · 82 citations
Chemistry · Engineering · Physics and Astronomy · #Angle-resolved photoemission spectroscopy #Atomic orbital #Band gap #Chemistry #Computational chemistry #Condensed matter physics #Density functional theory #Electronic band structure #Electronic structure #Hybrid functional #Materials science #Molecular physics #Nuclear magnetic resonance #Organic Electronics and Photovoltaics #Perovskite Materials and Applications #Photoemission spectroscopy #Physics #Quantum mechanics #Semiconductor materials and devices #Valence (chemistry) #X-ray photoelectron spectroscopy #cond-mat.mtrl-sci
paper · pdf · doi:10.1103/physrevb.90.075204
published in Physical Review B 90(7) (American Physical Society)
openalex publication_date 2014/08/25 · arxiv created 2015/08/19 · arxiv updated 2015/08/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
The energy positions of frontier orbitals in organic electronic materials are often studied experimentally by (inverse) photoemission spectroscopy and theoretically within density functional theory. However, standard exchange-correlation functionals often result in too small fundamental gaps, may lead to wrong orbital energy ordering, and do not capture polarization-induced gap renormalization. Here we examine these issues and a strategy for overcoming them by studying the gas phase and bulk electronic structure of the organic molecule quinacridone (5Q), a promising material with many interesting properties for organic devices. Experimentally we perform angle-resolved photoemission spectroscopy (ARUPS) on thin films of the crystalline \ensuremathβ phase of 5Q. Theoretically we employ an optimally tuned range-separated hybrid functional (OT-RSH) within density functional theory. For the gas phase molecule, our OT-RSH result for the ionization potential (IP) represents a substantial improvement over the semilocal PBE and the PBE0 hybrid functional results, producing an IP in quantitative agreement with experiment. For the bulk crystal we take into account the correct screening in the bulk, using the recently developed optimally tuned screened range-separated hybrid (OT-SRSH) approach, while retaining the optimally tuned parameters for the range separation and the short-range Fock exchange. This leads to a band gap narrowing due to polarization effects and results in a valence band spectrum in excellent agreement with experimental ARUPS data, with respect to both peak positions and heights. Finally, full-frequency G0W0 results based on a hybrid functional starting point are shown to agree with the OT-SRSH approach, improving substantially on the PBE-starting point.