Power sources that can be charged anytime and anywhere are highly desirable for mobile devices. The most suitable device for achieving such wireless charging is a photocapacitor, which utilizes light as a renewable energy source instead of electricity from the grid. Sunlight on Earth is intermittent and unstable, so photocapacitors that can be charged by the day or room light and near-infrared (near-IR) radiation are needed to ensure the uninterrupted operation of the equipment. We employ a single dye-sensitized solar cell as a photocapacitor without adding any additional charge storage components to reduce the cost and complexity of device manufacturing. To realize such photocapacitors, this work presents a family of new isoindigo-based D-π-A photoactive dyes with good visible and near-IR absorption. Notably, LF15 has a higher molar absorbance coefficient and enhanced dye-loading than LF23, which is consistent with the higher photocurrent of photocapacitors based on the former. Photocapacitors based on these three dyes achieve photovoltages up to 0.74 V, area-specific capacitances of 2.87 mF cm-2 , and excellent charge-discharge stability. The devices can be charged in both visible and near-IR conditions, exhibiting typical capacitor behavior.
Keywords: Dye-sensitized solar cell; Isoindigo; Photocapacitor; Visible and near-infrared sensitizers; Wireless charging.
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