title: Quasiparticle Level Alignment for Photocatalytic Interfaces.
abstract: Electronic level alignment at the interface between an adsorbed molecular layer and a semiconducting substrate determines the activity and efficiency of many photocatalytic materials. Standard density functional theory (DFT)-based methods have proven unable to provide a quantitative description of this level alignment. This requires a proper treatment of the anisotropic screening, necessitating the use of quasiparticle (QP) techniques. However, the computational complexity of QP algorithms has meant a quantitative description of interfacial levels has remained elusive. We provide a systematic study of a prototypical interface, bare and methanol-covered rutile TiO2(110) surfaces, to determine the type of many-body theory required to obtain an accurate description of the level alignment. This is accomplished via a direct comparison with metastable impact electron spectroscopy (MIES), ultraviolet photoelectron spectroscopy (UPS), and two-photon photoemission (2PP) spectroscopy. We consider GGA DFT, hybrid DFT, and G0W0, scQPGW1, scQPGW0, and scQPGW QP calculations. Our results demonstrate that G0W0, or our recently introduced scQPGW1 approach, are required to obtain the correct alignment of both the highest occupied and lowest unoccupied interfacial molecular levels (HOMO/LUMO). These calculations set a new standard in the interpretation of electronic structure probe experiments of complex organic molecule/semiconductor interfaces.
authors.affiliation: ICN2-Institut Català de Nanociència i Nanotecnologia and CSIC-Consejo Superior de Investigaciones Cientificas , ICN2 Building, Campus UAB, E-08193 Bellaterra (Barcelona), Spain.|Nano-Bio Spectroscopy Group and ETSF Scientific Development Center, Departamento de Física de Materiales, Centro de Física de Materiales CSIC-UPV/EHU-MPC and DIPC, Universidad del País Vasco UPV/EHU , E-20018 San Sebastián, Spain.
authors.forename: Annapaoala
authors.initials: A
authors.lastname: Migani
authors.affiliation: Nano-Bio Spectroscopy Group and ETSF Scientific Development Center, Departamento de Física de Materiales, Centro de Física de Materiales CSIC-UPV/EHU-MPC and DIPC, Universidad del País Vasco UPV/EHU , E-20018 San Sebastián, Spain.
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Mowbray
authors.affiliation: Department of Physics and ICQD/HFNL, University of Science and Technology of China , Hefei, Anhui 230026, China.|Synergetic Innovation Center of Quantum Information & Quantum Physics, University of Science and Technology of China , Hefei, Anhui 230026, China.
authors.forename: Jin
authors.initials: J
authors.lastname: Zhao
authors.affiliation: Department of Physics and Astronomy, University of Pittsburgh , Pittsburgh, Pennsylvania 15260, United States.
authors.forename: Hrvoje
authors.initials: H
authors.lastname: Petek
authors.affiliation: Nano-Bio Spectroscopy Group and ETSF Scientific Development Center, Departamento de Física de Materiales, Centro de Física de Materiales CSIC-UPV/EHU-MPC and DIPC, Universidad del País Vasco UPV/EHU , E-20018 San Sebastián, Spain.
authors.forename: Angel
authors.initials: A
authors.lastname: Rubio