Synergistic optimization of light absorption and thermal conductance in flexible VACNT-based solar thermal layers

Flexible super-black absorbers with high absorbance and thermal conductance show great potential for solar thermal applications. Vertically aligned carbon nanotube (VACNT) arrays are widely used due to their unique structure, offering excellent optical and energy transfer properties. The challenge is to enhance both absorbance and thermal conductance while maintaining flexibility. In this study, we systematically optimize the structural parameters of VACNT arrays—including tube diameter, length, spacing, and incident angle—based on optical and thermal modeling. The influence of different flexible embedding media is also examined. Under optimal conditions, the VACNT array achieves a thermal conductance of 1043.07 W/K and an equivalent absorption rate of 98.60 %. With Polydimethylsiloxane (PDMS) as the embedding medium, the absorption performance further increases to 99.51 %. These results demonstrate that the proposed VACNT-based design achieves synergistic improvement in both light absorption and thermal transfer. The method provides a novel and scalable strategy for developing high-performance, flexible photothermal materials, with promising applications in wearable electronics, solar-thermal energy harvesting, and adaptive energy management systems. • Optical and thermal models for VACNT arrays are established. • Achieved synergistic enhancement of light absorption and thermal conductivity. • Flexible medium endows VACNT arrays with flexibility and adaptability. • Reference for next-gen flexible photothermal materials is provided.