Desolvation-Induced Versatile Transfer Printing of Binder-Free Boron Nitride Film with Thermal, Optical Dual Functionality

Hexagonal boron nitride (BN) is a 2D material consisting of alternating sp² hybridized B and N atoms with structural similarities with graphite. Although BN nanostructures have recently received significant attention due to unique physical and chemical properties that lend promise for practical use, their applications have been hindered by an absence of processability and poor alignment quality. To compensate the disadvantage of BN, additional binders were mainly added in conventional approaches but has been dilute physical properties of BN applications. Herein we report highly effective and versatile transfer-printing of the binder-free BN layer onto a variety of substrates based on the desolvation-induced adhesion switching (DIAS) phenomenon. The dense array of BN components with strong alignment were gained through functionalization of BN sheets and rational selection of membrane surface energy combined with systematic control of solvation and desolvation status permit extensive tunability of interfacial interactions at BN-BN, BN-membrane, and BN-substrate boundaries. Therefore, without integrating any additives in the BN film and applying any surface treatment on target substrates, DIAS achieves a near 100 % transfer yield of binder-free BN films on diverse substrates, including substrates with non-planar and significant surface irregularities. The printed BNs exhibit high optical transparency (> 90 %) and excellent thermal conductivity (167 > Wm^-1K^-1) for few-µm-thick films due to their dense and well-ordered microstructures. In addition to superior heat dissipation capability, owing to birefringence and anisotropic nanostructure of the BN film, substantial optical enhancement effects of light extraction and diffusive properties were confirmed by simulative studies. As a result, we demonstrate that substantial improvement of energy conversion of light-emitting and light-harvesting devices, demonstrating their remarkable promise for next-generation optoelectronic device platforms.