Selectively Transparent Tannic Acid-Grafted MoS ₂ /Cu _1.95 S Heterojunction Membranes with Enhanced Photothermal Conversion

For effective solar radiation management, windows in sustainable buildings need to feature high visible light transmittance to support daylighting needs, block unwanted solar radiation, and maintain an appropriate photothermal performance. However, materials with a high photothermal performance usually do not exhibit favorable light transmittance. Here, the selectively transparent photothermal tannic acid-grafted Cu_1.95S and MoS₂ heterojunction (Cu_1.95S/TA-MoS₂) was prepared with a mild one-pot synthesis. On the one hand, TA not only grafts both MoS₂ and Cu_1.95S but also effectively absorbs ultraviolet light. On the other hand, the incorporation of Cu_1.95S enhances near-infrared absorption. The selectively transparent photothermal membrane was fabricated by blending Cu_1.95S/TA-MoS₂ with poly(vinyl alcohol). Compared with the TA-MoS₂ membrane, the Cu_1.95S/TA-MoS₂ membrane achieved a 25.3% reduction in solar transmittance with only a 6.3% loss in luminous transmittance. Moreover, via Cu_1.95S with localized surface plasmon resonance properties and a synergistic effect with MoS₂, the photothermal equilibrium temperature of the Cu_1.95S/TA-MoS₂ membrane was increased by 23.4 °C. The membrane demonstrates effective antifogging capability and generates a stable voltage of 0.14 V when integrated with thermoelectric modules. This work provides solid support for next-generation solar radiation management in building windows.