A New-Type Photovoltaic Cell Using Photochemical Reaction of Fullerene

Abstract

Fullerene, C₆₀, is readily reduced to its anion radical, C₆₀^•−, in nitrobenzene (NB) that contains a tetraphenylborate ion (TPB⁻) under irradiation with visible light. Fullerene excited by visible light withdraws one electron from TPB⁻ to form C₆₀^•− and generated TPB radical decomposes. C₆₀^•− can be stored for several days without any changes in deaerated NB. However, as soon as the NB solution containing C₆₀^•− is bubbled with air, C₆₀^•− immediately oxidizes to C₆₀. Using this photochemical reaction of C₆₀, we have developed a new-type of photovoltaic cell that can generate and store electricity. We call this cell a photoelectrochemical condenser (PEC). The anodic reaction of the PEC is the oxidation of C₆₀^•− to C₆₀; although many reduction reactions are possible, the cathodic reaction is chosen to be the reduction of Fe³⁺ to Fe²⁺ in an aqueous phase. When the PEC was irradiated with visible light ranging from 400 nm to 700 nm (23.4 mW cm⁻²), the electromotive force was measured to be approximately 1100 mV, and an electric current of approximately 2 mA was observed. In this paper, we present the PEC and discuss its performance for generating and storing electricity.