Photochemical Determinants of the Efficiency of Photogalvanic Conversion of Solar Energy

Abstract

A photogalvanic cell is a battery in which the cell solution absorbs light directly to generate species which, upon back reaction through an external circuit with the aid of suitable electrodes, produces electric power; photoactivation of the electrodes is 'not involved. The charge-carrying species have storage capacity if they are long-lived and can be prevented from engaging in degradativc back reactions in bulk solution. The efficiency of a photogalvanic cell for the conversion of photon energy into electrical energy is determined by photochemical and electrochemical factors. Among the latter are the choice of electrode materials and the kinetics of electron transfer at the heterogeneous surfaces. In this paper we examine '"the photochemical determinants of the efficiency of photogalvanic eel] operation: the absorption spectral characteristics of the cell solution, the efficiency of formation of separated charge carriers, and the lifetimes of the carriers toward back electron transfer. Modulation of bulk solution dynamics can be achieved by variation of the solution medium. The photochemical determinants are discussed with particular reference to the use of thionine or Ru(bpy)2+ as the light absorbing species.

Studies of the Micellar Effect on Photogalvanics: Solar Energy Conversion and Storage—EDTA-Safranine O-NaLS System

“…Theoretical conversion efficiency of photogalvanic cells is about 18%, but the observed conversion efficiencies are quite low due to lower stability of dyes, back-electron transfer, aggregation of the dye molecules around electrode, etc. Hoffman and Lichtin (1979) have discussed various problems encountered in the development of this field.…”

Studies of effect of heterocyclic dyes in photogalvanic cells for solar energy conversion and storage: NaLS-ascorbic acid system

“…The photogalvanic effect was first observed by Rideal and Williams 1 , systematically investigated by Rabinowitch 2,3 and later by various other workers. [4][5][6][7][8] Hoffman and Lichtin 9 have discussed various problems encountered in the development of this field. A detailed literature survey reveals that different photosensitizers have been used in photogalvanic cells along with reductants and surfactants.…”