Electronic and chemical structure of an organic light emitter embedded in an inorganic wide-bandgap semiconductor: Photoelectron spectroscopy of layered and composite structures of Ir(BPA) and ZnSe

Journal Article · Thu May 07 00:00:00 EDT 2015 · Journal of Applied Physics

DOI:https://doi.org/10.1063/1.4919828· OSTI ID:22403013

Dimamay, Mariel ^[1]; Mayer, Thomas; Jaegermann, Wolfram ^[1]; Hadziioannou, Georges ^[2]

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1. Institute of Materials Science, Darmstadt University of Technology, Alarich-Weiss-Strasse 2, D-64287 Darmstadt (Germany)
2. Laboratoire de Chimie des Polymères Organiques, CNRS, Université de Bordeaux, UMR 5629-16 Avenue Pey-Berland, 33607 Pessac (France)

Luminescent organic phases embedded in conductive inorganic matrices are proposed for hybrid organic-inorganic light-emitting diodes. In this configuration, the organic dye acts as the radiative recombination site for charge carriers injected into the inorganic matrix. Our investigation is aimed at finding a material combination where the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) of the organic dye are situated in between the valence and conduction bands of the inorganic matrix in order to promote electron and hole transfer from the matrix to the dye. Bilayer and composite thin films of zinc selenide (ZnSe) and a red iridium complex (Ir(BPA)) organic light emitter were prepared in situ via UHV thermal evaporation technique. The electronic and atomic structures were studied applying X-ray and ultraviolet photoelectron spectroscopies. The measured energy band alignments for the ZnSe/Ir(BPA) bilayer and ZnSe+Ir(BPA) composite reveal that the HOMO and LUMO of the organic dye are positioned in the ZnSe bandgap. For the initial steps of ZnSe deposition on a dye film to form Ir(BPA)/ZnSe bilayers, zinc atoms intercalate into the dye film leaving behind an excess of selenium at the interface that partly reacts with dye molecules. Photoelectron spectroscopy of the composites shows the same species suggesting a similar mechanism. This mechanism leads to composite films with increased content of amorphous phases in the inorganic matrix, thereby affecting its conductivity, as well as to the presence of nonradiative recombination sites provided by the intercalated Zn atoms.

• OSTI ID: 22403013
• Journal Information: Journal of Applied Physics, Vol. 117, Issue 17; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA); ISSN 0021-8979
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COMPOSITE MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRONIC STRUCTURE
ELECTRONS
ENERGY GAP
HOLES
INTERFACES
IRIDIUM COMPLEXES
LAYERS
LIGHT EMITTING DIODES
MOLECULAR ORBITAL METHOD
PHOTOELECTRON SPECTROSCOPY
RECOMBINATION
SEMICONDUCTOR MATERIALS
THIN FILMS
ULTRAVIOLET RADIATION
VISIBLE RADIATION
ZINC
ZINC SELENIDES