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Title: Orbital alignment at the internal interface of arylthiol functionalized CdSe molecular hybrids

Organic-inorganic nanoparticle molecular hybrid materials are interesting candidates for improving exciton separation in organic solar cells. The orbital alignment at the internal interface of cadmium selenide (ArS-CdSe) hybrid materials functionalized with covalently attached arylthiolate moieties was investigated through X-ray photoemission spectroscopy (XPS) and ultraviolet photoemission spectroscopy (UPS). A physisorbed interface between arylthiol (ArSH) ligands and CdSe nanoparticles was also investigated for comparison. This interface was created via a multi-step thin film deposition procedure in-vacuo, where the surface was characterized after each experimental step. This enabled the direct comparison of ArSH/CdSe interfaces produced via physisorption and ArS-CdSe covalently attached hybrid materials, which rely on a chemical reaction for their synthesis. All material depositions were performed using an electrospray deposition, which enabled the direct injection of solution-originating molecular species into the vacuum system. This method allows XPS and UPS measurements to be performed immediately after deposition without exposure to the atmosphere. Transmission electron microscopy was used to determine the morphology and particle size of the deposited materials. Ultraviolet-visible spectroscopy was used to estimate the optical band gap of the CdSe nanoparticles and the HOMO-LUMO gap of the ArSH ligands. These experiments showed that hybridization via covalent bonds results in an orbital realignmentmore » at the ArSH/CdSe interface in comparison to the physisorbed interface. The orbital alignment within the hybrid caused a favorable electron injection barrier, which likely facilitates exciton-dissociation while preventing charge-recombination.« less
Authors:
;  [1] ; ; ;  [2]
  1. Department of Electrical Engineering, University of South Florida, Tampa, Florida 33620 (United States)
  2. Department of Materials Science and Engineering and Molecular Engineering and Sciences Institute, University of Washington, Box 352120, Seattle, Washington 98195-2120 (United States)
Publication Date:
OSTI Identifier:
22402893
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Applied Physics; Journal Volume: 117; Journal Issue: 15; Other Information: (c) 2015 AIP Publishing LLC; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; CADMIUM SELENIDES; CHEMICAL BONDS; COMPARATIVE EVALUATIONS; COVALENCE; ELECTRON BEAM INJECTION; EXCITONS; INTERFACES; MORPHOLOGY; NANOPARTICLES; ORGANIC SOLAR CELLS; PARTICLE SIZE; RECOMBINATION; SURFACES; THIN FILMS; THIOLS; TRANSMISSION ELECTRON MICROSCOPY; ULTRAVIOLET RADIATION; X-RAY PHOTOELECTRON SPECTROSCOPY