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.

Simplified photogalvanic cell design with promise for the enhanced solar electricity generation and storage

“…11 The solar conversion efficiency 0.06% is reported for primitive beaker photogalvanic cell design (two chambered design). 61 Later on, cell design was changed by Shigehara et al to a glass chamber having two compartments (Pt electrode used in each compartment) separated by a spacer for which potential 190 mV and current 2.7 μA is reported. 48 Kamat et al observed potential 170 mV for homogeneous photogalvanic cell designed with three electrodes that is, two working (anode and cathode) and one reference saturated calomel electrode.…”

Energy Conversion and Storage Potential of Photogalvanic Cell Based on Ethylenediaminetetraacetic Acid—New Methylene Blue plus Fast Green

“…Fill factor (n) = V pp i pp /V oc i sc (6) Conversion efficiency = V pp × i pp /10.4(mW/cm 2 ) × 100 per cent (7) where V pp , i pp , V oc , and i sc are the potential at power point, current at power point, open circuit voltage, and the short circuit current. The system at its optimum condition is exposed to sunlight.…”

“…From the literature survey [2][3][4][5][6][7][8][9] of photogalvanic cells with different dyes, it is observed that photochemical solar energy conversion and storage depend on structures, reduction potential, and absorption maxima of dyes used in the cells. To utilize the broad solar spectrum, mixed dyes instead of a single dye may be used in solar cell [10,11].…”