title: Lead-iodide nanowire perovskite with methylviologen showing interfacial charge-transfer absorption: a DFT analysis.
abstract: Methylviologen lead-iodide perovskite (MVPb2I6) is a self-assembled one-dimensional (1-D) material consisting of lead-iodide nanowires and intervening organic electron-accepting molecules, methylviologen (MV(2+)). MVPb2I6 characteristically shows optical interfacial charge-transfer (ICT) transitions from the lead-iodide nanowire to MV(2+) in the visible region and unique ambipolar photoconductivity, in which electrons are transported through the three-dimensional (3-D) organic network and holes along the 1-D lead-iodide nanowire. In this work, we theoretically study the electronic band-structure and photocarrier properties of MVPb2I6 by density functional theory (DFT) calculations. Our results clearly confirm the experimentally reported type-II band alignment, whose valence band mainly consists of 5p (I) orbitals of the lead-iodide nanowires and the conduction band of the lowest unoccupied molecular orbital of MV(2+). The DFT calculation also reveals weak charge-transfer interactions between the lead-iodide nanowires and MV(2+). In addition, the electronic distributions of the valence and conduction bands indicate the 3-D transport of electrons and 1-D transport of holes, supporting the reported experimental result.
authors: Research Center for Advanced Science and Technology (RCAST), The University of Tokyo, 4-6-1 Komaba, Meguro-ku, Tokyo 153-8904, Japan. ufujisw@mail.ecc.u-tokyo.ac.jp.
authors: Jun-ichi
authors: J
authors: Fujisawa
authors: Giacomo
authors: G
authors: Giorgi
mesh_terms: D065638:Absorption, Radiation; D017610:Calcium Compounds / Q000737:chemistry*; D003198:Computer Simulation; D004553:Electric Conductivity; D004579:Electron Transport; D007454:Iodides / Q000737:chemistry*; D007854:Lead / Q000737:chemistry*; D008956:Models, Chemical; D008958:Models, Molecular; D053770:Nanowires / Q000737:chemistry* / Q000648:ultrastructure*; D010087:Oxides / Q000737:chemistry*; D010269:Paraquat / Q000737:chemistry*; D055672:Static Electricity; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry*
chemical_list: D017610:Calcium Compounds; D007454:Iodides; D010087:Oxides; C059910:perovskite; D007854:Lead; D014025:Titanium; D010269:Paraquat