Title

Complementary Roles Of Benzylpiperazine And Iodine 'Vapor' In The Strong Enhancement Of Orange Photoluminescence From Cui(1 1 1) Thin Film

Keywords

CuI; cuprous iodide; defect states; nanostructures; photoluminescence

Abstract

We have employed density functional theory, corrected by the on-site electron-electron repulsion energy U, to clarify the mechanism behind the enhanced orange photoluminescence (PL) of a CuI(1 1 1) thin film conjugated with a benzylpiperazine (BZP) molecule in the presence of an iodine 'vapor' atom. Our results demonstrated that the adsorbed molecule and the 'vapor' atom play complementary roles in producing the PL. The latter, in attaching to the film surface, creates a hole-trapping surface state located ∼0.25 eV above the valence band-edge of the film, in good agreement with ∼0.2 eV reported in experiments. Upon photo-excitation of the BZP/CuI(1 1 1) system in the presence of surface iodine 'vapor' atoms, excited electrons are transferred into the conduction band of CuI, and holes are trapped by the 'vapor' atoms. These holes, in turn, quickly relax into the HOMO state of the BZP molecule, owing to the fact that the molecule adsorbs on the film surface in the immediate vicinity of a 'vapor' atom. Relaxed holes subsequently recombine with excited electrons in the conduction band of the CuI film, thereby producing a luminescence peak at ∼2.1 eV, in qualitative agreement with experimental findings. © 2014 IOP Publishing Ltd.

Publication Date

5-7-2014

Publication Title

Journal of Physics Condensed Matter

Volume

26

Issue

18

Number of Pages

-

Document Type

Article

Personal Identifier

scopus

DOI Link

https://doi.org/10.1088/0953-8984/26/18/185005

Socpus ID

84899418022 (Scopus)

Source API URL

https://api.elsevier.com/content/abstract/scopus_id/84899418022

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