Mitigating Cracks on Mesomorphic Ceramic Films Prepared by Blade-Coatin

Mesomorphic ceramics, defined as inorganics with static liquid crystalline superstructures, can serve as waveplates, achieving cost-efficient polarization control. The optical retardance of a waveplate requires a sufficient thickness. However, crack formation upon thermal treatment of mesomorphic ceramics degrades both optical and mechanical properties. To mitigate crack formation, we fabricate 2-µm-thick mesomorphic ceramic films of ZnO using three different blade-coating methods: treatment of blade-coated films with ZnO precursors, subsequent blade coating of multiple thin layers of nanorods to fill cracks, and a hybrid approach involving multiple layers and precursor treatment. Using the hybrid approach, a 2-µm-thick MC film with a birefringence of 0.088 and a transparency of 82% at 1065 nm was achieved. This reported method to mitigate cracks in sintered mesomorphic ceramics takes a critical step toward crack-free, wide-area, inorganic waveplates. Crack-free mesomorphic ceramic films could benefit diverse applications including thin-film transistors, optoelectronics, and photocatalysis.