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Photoelectrochromic Characteristics of Photoelectrochemical Imaging System with a Semiconductor/Solution (Metallic Ion) Junction
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1980
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Metallic IonOptical MaterialsEngineeringPhotoelectrochemical Imaging SystemPhoto-electrochemical CellPhotoelectrochemistrySemiconductorsChemical EngineeringElectronic DevicesPhotoelectric SensorSemiconductor InterfacesPhotocatalysisElectrical EngineeringImage FormationPhotochemistryPhotoelectric MeasurementPhotoelectric SensorsPhotodegradationPhotochromismElectrochemistryApplied PhysicsPhotoelectrochromic CharacteristicsSemiconductor ElectrodesImagingOptoelectronicsReversible Imaging System
Photoelectrochemical reactions at semiconductor electrodes in metallic‑ion solutions enable reversible imaging. The study investigates electrochemical characteristics of semiconductor photoelectrodes, focusing on charge transfer across the semiconductor/solution junction. Image formation occurs under light absorption when n‑type electrodes are anodically polarized or p‑type cathodically polarized, and erasing is achieved by reversing the polarity or opening the circuit. Visible images were produced on n‑ and p‑type semiconductors with Tl⁺, Pb²⁺, Co²⁺, and Ag⁺; a brown pattern on a sintered n‑type electrode remained stable for over 20,000 h and could be readily erased, demonstrating reversible imaging.
Photoelectrochemical reactions at semiconductor electrodes in solutions containing metallic ions have been applied to a reversible imaging system. Clearly visible images were formed on the surfaces of , , and (n‐type) and (p‐type) semiconductor electrodes in solutions with metallic ions such as Tl+, Pb2+, Co2+, and Ag+ as image‐forming agents. Image formation occurs under irradiation with light absorbable by the semiconductors, while semiconductor electrodes are polarized either anodically (for n‐type) or cathodically (for p‐type). Erasing can be accomplished only by polarizing the semiconductor electrodes cathodically (n‐type) or anodically (p‐type), or the image can be held if desired by opening the circuit after the image formation process. For example, a brown image pattern was formed on a sintered n‐type photoelectrode in an aqueous solution containing Tl+when the electrode was anodically polarized (1.0V vs. SCE) under irradiation with absorbable light. The image was stable for more than 20,000 hr in air, but faded immediately when cathodic polarization of −0.5V vs. SCE was applied at a electrode. This imaging process has good reversibility during image formation and erasing. Electrochemical characteristics based on the semiconductor photoelectrode reactions were investigated and discussed focusing on charge transfer across the semiconductor/solution junction.