Elektrochemische Untersuchungen zur spektralen Sensibilisierung von ZnO‐Einkristallen

Abstract

Sensitised photo-currents can be observed with a ZnO-crystal if it is placed in contact with an electrolyte to which a suitable dyestuff has been added and if its surface is then irradiated with light of a wavelength which is absorbed only by the dyestuff. The ZnO crystal must act as the anode of a galvanic cell and thus be at a positive potential. Measurements are reported using Rhodamine B, Riboflavin and Rose Bengal as sensitizers. For Rose Bengal the effect of over-sensitisation could also be observed on addition of reducing agents such as hydroquinone, NaaSOa or HaO a. The method of investigation applied here offers new possibilities for the study of the mechanism of photosensitization. The mechanisms which are compatible with the results obtained here are discussed in detail at the end of the paper. 437Eisleiteng. [1][2][3][4][5].

Molecular photovoltaics that mimic photosynthesis

“…This places the electron recapture clearly in the inverted Markus region, reducing its rate by several orders of magnitude. This provides also a rationale for the observation that this interfacial redox process is almost independent of temperature and is surprisingly insensitive to the ambient that is in contact with the film [10].…”

Dye-sensitized Solar Cells

“…It was later found that the photosensitivity can be extended to longer wavelengths by adding a dye to silver halide emulsions [2]. The interest in photoelectrochemistry of semiconductors led to the discovery of wet-type photoelectrochemical solar cells [3][4][5]. Grätzel has then extended the concept to OPEN ACCESS the dye sensitized solar cells (DSSC) by adsorption of dye molecules on the nanocrystalline TiO 2 electrodes.…”

Photo-induced dissolution of zinc in alkaline solutions

“…It has been reported, in many cases, that the electrochemical behaviour of these passive layers is similar to that of the non-stoichiometric ZnO [3][4][5][6], which is an n-type semiconductor with a band-gap energy of approximately 3.2 eV [7,8]. Although, the photo-electrochemical properties of these oxide layers have been studied in some detail [9,10], little attention has been devoted to the possible modifications of the oxides induced by the illumination procedure.…”