Wood Reconfiguration Enables Broadband Blackbody in Large‐Area, Modular, Optically Welded Carbon Constructs

Abstract A broadband blackbody requires both perfect anti‐reflective characteristics and effective light entrapment spanning wavelengths from the mid‐infrared (MIR) to the ultraviolet (UV) range. This ideal combination has not been achieved in several artificial superblack systems or even in naturally occurring superblack structures. A broadband blackbody is created by carbonizing delignified wood infused with lignin particles (LPs), forming a reconfigured wood (cRW) system. The LPs enhance the dimensional fidelity of cRW and promote the development of sparse, highly aligned fibrillar microstructures, achieving super‐absorbance levels spanning from the MIR to the UV wavelengths, reaching over 99.8% absorption. This performance is further amplified in large‐area light traps constructed from tiled cRW, which are optically welded, modular and customizable in size and shape. The tiled cRW configuration effectively eliminates thermal ghost reflections and outperforms individual cRW units. This system is demonstrated as a perfect broadband blackbody, which can act as promising reference infrared radiator in IR thermography that benefit from precise sensor calibration. Altogether, this optically welded superabsorber trap introduces a wood‐based solution for broadband blackbody materials, opening new opportunities across diverse applications.