The Polymer Society of Korea

Abstract

An energy-cycling electrochromic smart window converts indoor–outdoor photothermal losses into electricity. A covalently grafted CoPc–PANI hybrid with a TiO2 nanofiber outer layer enables faster charge transfer, improved redox reversibility and cycling stability, and stronger NIR absorption for enhanced photothermal conversion, while preserving transparency and boosting energy storage. The device provides tunable visible–NIR electrochromism (cooling, warming, heating) and, paired with thermoelectrics, forms a closed photothermal–electrical recovery loop. EnergyPlus simulations across climates show meaningful energy savings, indicating potential for low-carbon buildings. Future work is for scalable fabrication, long-term cycling validation, and integration with building energy management systems.