Quantum Efficiency (Φ) Enhancement of p-CuI Sensitized LB Films of Methylviolet-C18 by Minimizing Dye Aggregates
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Date
2015
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Publisher
Uva Wellassa University of Sri Lanka
Abstract
It is well known that the spectral response of wide band gap semiconductor materials can be
extended to the visible region by deposition of suitable dyes on the surface (Senadeera et al., 2005;
Fernando et al., 2013). In addition to the adustability of the spectral response, dye sensitized solar
cells have several advantages (Kubo et al., 2002). The dye sensitized photocurrent is rather
insensitive to the impurites and the defects of the semiconductor. When dyes with intense
absorption bands are deposited, the light absorption at the sensitized surface becomes much higher
than a bare semiconductor surface. Although the absorption properties of the dye increases with
the concentration of the absorbed dye on the semiconductor surface, a dye sensitized photocurrent
enhacement cannot be observed with the increase of the number of dye molecules on the
semicondutor because of the energy dissipative proceses of the excited states of the dye and the
recombination of photogenerated charge carriers (Fernando et al., 1994).
Methodology
Commercially available well cleaned copper sheets (1cmx3cm) were used to deposit p-CuI nano
thin films from the following method. A solution of CuI was prepared by dissolving 5mg of CuI
in 10ml of moisture free acetonitrile. CuI colloidal solution was lightly spread on the well cleaned
copper surface until forming a thickness ≈ 5.0 µm to prepare Cu/p-CuI photoelectrodes. Cu/p-
CuI photoelectrodes were used to deposit LB films. Experimental set up used for LB deposition
is shown in the Fig.1 (Fernando et al., 2013). 2M KI and 1x10 M NaH2PO4- Na2HPO4 pH=6
buffer solution was used as the electrolyte. AFM pictures of the samples were obtained using a
Park’s AFMXE-70 Instrument. Photocurrent quantum efficiency (Ф%) was calculated using the
following equation,
Ф% = [number of electrons created / number of photons incident]x100%
Description
Keywords
Mineral Sciences, Materials Sciences, Science and Technology, Electronic Engineering, Nano Materials & Nanotechnology