P.M. Sirimanne

A dye-sensitized nano-porous solid-state photovoltaic cell

A photovoltaic cell was fabricated by sandwiching a monolayer of the pigment cyanidin adsorbed on nano-porous n-TiO2 film (deposited on conducting tin oxide glass) within a transparent polycrystalline film of p-CuI, filling the intercrystallite pores of the porous n-TiO2 film. Photoexcited dye is found to inject electrons into n-TiO2 and holes into p-Cul, generating photocurrents and photovoltages that are impressively high for a dye-sensitized solid-state photovoltaic cell.

Nanoporous TiO2 photoanode sensitized with the flower pigment cyanidin

The flower pigment cyanidin anchors into nanoporous films of TiO2 by surface complexation. A photoelectrochemical cell made from cyanidin-sensitized nanoporous TiO2, as a film deposited on conducting glass and with the I− + I3− redox couple in acetonitrile, generates high photocurrents of good stability.

Characterization of transparent conducting CuI thin films prepared by pulse laser deposition technique

Abstract Thin films of CuI were prepared by pulse laser deposition technique and their characteristics are studied. These films exhibited optical transmittance over 80% in the wavelength range 400–900 nm and minimum resistivity of about 2 K Ω cm. Blue shift in the onset of optical absorption of the CuI films is observed to that of polycrystalline powder of CuI.

On the photo-degradation of dye sensitized solid-state TiO2|dye|CuI cells

The space resolved photocurrent-imaging technique was used to investigate the degradation of dye sensitized solid-state TiO2|dye|CuI solar cells. In contrast to dye sensitized liquid cells only blurred and not sharp boundaries between illuminated and dark areas were observed. The deterioration of the cell was found to be much faster than in liquid dye sensitized cells and does not involve the sensitizer.

Deposition of thin polycrystalline films of cuprous thiocyanate on conducting glass and photoelectrochemical dye-sensitization

A method is given for electrochemical deposition of thin polycrystalline films of cuprous thiocyanate (p-type semiconductor, bandgap = 3.6 eV) on conducting indium-tin oxide glass. Dye-sensitization of the surface with methyl violet and construction of a photoelectrochemical cell are described. The investigation demonstrates the usefulness of unconventional high band gap semiconductors in studying dye-sensitization.

Identification of various luminescence centers in CuI films by cathodoluminescence technique

CuI films are prepared by different techniques at room temperature. An expansion of band gap energy was observed for the thin films prepared by pulse laser deposition technique. Various luminescence centers are identified in CuI films and different mechanisms are proposed for cathodoluminescence at different centers.

An approach for utilization of organic polymer as a sensitizer in solid-state cells

A solid-state cell was fabricated by sandwiching poly[2-methoxy-5(2 0 -ethyl-hexyloxy)-pphenylene vinylene] (MEH-PPV) in between micro-porous n-TiO2 and p-CuI films. The photo-excited polymer is found inject electrons into the conduction band of n-TiO2 and holes into the valance band of p-CuI. Maximum open-circuit voltage of 400 mV and short-circuit current of about 0.3 mA cm � 2 were observed for the TiO2|MEH-PPV|CuI cell, under white light illumination (100 mW cm � 2 ). r 2002 Elsevier Science B.V. All rights reserved.

A comparative study of semiconductor sensitization by micro-crystals of indium sulfide on various porous wide band gap semiconductor substrates

Abstract Semiconductor sensitization on various n-type wide band gap semiconductors was studied by micro-crystals of n-type indium sulfide. The generation of an anodic photocurrent on the electrode is explained from the viewpoint of semiconductor sensitization. A very high incident photon-to-current conversion efficiency (IPCE) of more than 80% was achieved on In 2 S 3 /In 2 O 3 electrodes in a polysulfide electrolyte. The observed values for the IPCE for In 2 S 3 /TiO 2 and In 2 S 3 /ZnO electrodes were rather low compared to that of In 2 S 3 /In 2 O 3 electrodes, in the same electrolyte. The semiconductor sensitization process was not observed on In 2 S 3 /ZnS electrodes. Different kinetics at the semiconductor/semiconductor interface are the reasons for the observed difference of the IPCE, for the electrodes.

Chlorophyll-sensitized microporous cuprous iodide photocathode

A method is given for deposition of a microporous film of cuprous iodide on indium-tin oxide glass substrate. Characteristics of the photocurrent spectra of the chlorophyll-sensitized film under back-wall and front-wall illumination are described.

Dye sensitization of low-bandgap semiconductor electrodes: cuprous oxide photocathode sensitized with methyl violet

When illuminated, dye-coated semiconductor electrodes inject electrons (holes) into the conduction (valence) band so that the photoresponse of high-bandgap semiconductors is extended to the visible region. It is found that when low-bandgap semiconductor electrodes are coated with dyes, the photocurrent in the bandgap region wavelengths is also enhanced. The effect is explained as originating from suppression of the recombination of carriers generated by photons captured directly by the semiconductor surface.