Interfacial electronic structure at the CH{sub 3}NH{sub 3}PbI{sub 3}/MoO{sub x} interface

Journal Article · Mon May 11 00:00:00 EDT 2015 · Applied Physics Letters

DOI:https://doi.org/10.1063/1.4921339· OSTI ID:22399068

Liu, Peng; Liu, Xiaoliang; Lyu, Lu; Xie, Haipeng; Zhang, Hong; Niu, Dongmei; Huang, Han ^[1]; Bi, Cheng; Xiao, Zhengguo; Huang, Jinsong ^[2]; Gao, Yongli ^[3]

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1. Institute of Super-Microstructure and Ultrafast Process in Advanced Materials, College of Physics and Electronics, Central South University, Changsha 410083 (China)
2. Department of Mechanical and Materials Engineering and Nebraska Center for Materials and Nanoscience, University of Nebraska-Lincoln, Lincoln, Nebraska 68588-0656 (United States)
3. Department of Physics and Astronomy, University of Rochester, Rochester, New York 14627 (United States)

Interfacial electronic properties of the CH{sub 3}NH{sub 3}PbI{sub 3} (MAPbI{sub 3})/MoO{sub x} interface are investigated using ultraviolet photoemission spectroscopy and X-ray photoemission spectroscopy. It is found that the pristine MAPbI{sub 3} film coated onto the substrate of poly (3,4-ethylenedioxythiophene) poly(styrenesulfonate)/indium tin oxide by two-step method behaves as an n-type semiconductor, with a band gap of ∼1.7 eV and a valence band edge of 1.40 eV below the Fermi energy (E{sub F}). With the MoO{sub x} deposition of 64 Å upon MAPbI{sub 3}, the energy levels of MAPbI{sub 3} shift toward higher binding energy by 0.25 eV due to electron transfer from MAPbI{sub 3} to MoO{sub x}. Its conduction band edge is observed to almost pin to the E{sub F}, indicating a significant enhancement of conductivity. Meanwhile, the energy levels of MoO{sub x} shift toward lower binding energy by ∼0.30 eV, and an interface dipole of 2.13 eV is observed at the interface of MAPbI{sub 3}/MoO{sub x}. Most importantly, the chemical reaction taking place at this interface results in unfavorable interface energy level alignment for hole extraction. A potential barrier of ∼1.36 eV observed for hole transport will impede the hole extraction from MAPbI{sub 3} to MoO{sub x}. On the other hand, a potential barrier of ∼0.14 eV for electron extraction is too small to efficiently suppress electrons extracted from MAPbI{sub 3} to MoO{sub x}. Therefore, such an interface is not an ideal choice for hole extraction in organic photovoltaic devices.

• OSTI ID: 22399068
• Journal Information: Applied Physics Letters, Vol. 106, Issue 19; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0003-6951
• Country of Publication: United States
• Language: English

Related Subjects

75 CONDENSED MATTER PHYSICS
SUPERCONDUCTIVITY AND SUPERFLUIDITY
BINDING ENERGY
DEPOSITION
ELECTRON TRANSFER
ELECTRONIC STRUCTURE
ELECTRONS
EMISSION SPECTROSCOPY
ENERGY LEVELS
FILMS
HOLES
INTERFACES
N-TYPE CONDUCTORS
PHOTOELECTRON SPECTROSCOPY
PHOTOVOLTAIC EFFECT
POTENTIALS
SUBSTRATES
TIN OXIDES
ULTRAVIOLET RADIATION
VALENCE
X-RAY SPECTROSCOPY