Photogalvanics: A sustainable and promising device for solar energy conversion and storage

Photogalvanic cells are based on the photogalvanic effect; provide an additional method on acquiring energy, converting sunlight into electricity and its storage. Production of potential between two electrodes separated by suitable substances in which the influence of light on the electrode potential is due to a photochemical process in the body of the electrolyte is termed as the Becquerel effect so called photogalvanic effect. In this review we have proposed suitable classification of solar cell based on the excitation (direct or indirect) of electron and semiconductor used, in which the photogalvanic cell has potential to revolutionize the existing solar cells due to its low cost and inherent storage capacity. Various type of photogalvanic effect has been discussed as linear photogalvanic, circular photogalvanic and photogalvanomagnetic effect. The main purpose of the paper is to review the results of research published related to this phenomenon and to propose the mechanism for the photocurrent generation in detail. Here, we have reviewed around 400 research articles/patents/reports/proceedings in the development of photogalvanic cells, from early stage to recently more efficient; considering electrolyte, electrode material and assembly set up. The results of electrical parameters (open circuit potential, short circuit current, power at power point, fill factor, conversion efficiency and storage capacity) of the photogalvanic cells containing dye, reductant and surfactants have given in a tabular form with comparison of more than 150 systems. A vast collection of photogalvanic systems and their electrical parameters have been scrutinized for further research work to enhance the electrical output and to make it commercially viable. In this paper, the primitive photogalvanic systems with iron-thionine to recent dye-reductant-surfactant system with specific reference to chronological and technological development in the cell have been discussed. We have also focused on the challenges and limitations in the field of photochemical conversion of solar energy and its storage.