Pan Jia-Ahn, Rong Zichao, Wang Yuanyuan, Cho Himchan, Coropceanu Igor, Wu Haoqi, Talapin Dmitri V
Department of Chemistry, James Franck Institute, and Pritzker School of Molecular Engineering, University of Chicago, Chicago, Illinois 60637, United States.
Center for Nanoscale Materials, Argonne National Laboratory, Argonne, Illinois 60439, United States.
J Am Chem Soc. 2021 Feb 10;143(5):2372-2383. doi: 10.1021/jacs.0c12447. Epub 2021 Jan 28.
Spatially patterned dielectric materials are ubiquitous in electronic, photonic, and optoelectronic devices. These patterns are typically made by subtractive or additive approaches utilizing vapor-phase reagents. On the other hand, recent advances in solution-phase synthesis of oxide nanomaterials have unlocked a materials library with greater compositional, microstructural, and interfacial tunability. However, methods to pattern and integrate these nanomaterials in real-world devices are less established. In this work, we directly optically pattern oxide nanoparticles (NPs) by mixing them with photosensitive diazo-2-naphthol-4-sulfonic acid and irradiating with widely available 405 nm light. We demonstrate the direct optical lithography of ZrO, TiO, HfO, and ITO NPs and investigate the chemical and physical changes responsible for this photoinduced decrease in solubility. Micron-thick layers of amorphous ZrO NPs were patterned with micron resolution and shown to allow 2π phase control of visible light. We also show multilayer patterning and use it to fabricate features with different thicknesses and distinct structural colors. Upon annealing at 400 °C, the deposited ZrO structures have excellent optical transparency across a wide wavelength range (0.3-10 μm), a high refractive index ( = 1.84 at 633 nm), and are optically smooth. We then fabricate diffractive optical elements, such as binary phase diffraction gratings, that show efficient diffractive behavior and good thermal stability. Different oxide NPs can also be mixed prior to patterning, providing a high level of material tunability. This work demonstrates a general patterning approach that harnesses the processability and diversity of colloidal oxide nanomaterials for use in photonic applications.
空间图案化的介电材料在电子、光子和光电器件中无处不在。这些图案通常通过利用气相试剂的减法或加法方法制成。另一方面，氧化物纳米材料溶液相合成的最新进展开启了一个具有更大成分、微观结构和界面可调性的材料库。然而，将这些纳米材料图案化并集成到实际器件中的方法尚不完善。在这项工作中，我们通过将氧化物纳米颗粒（NPs）与光敏重氮-2-萘酚-4-磺酸混合并用广泛使用的405nm光照射，直接对其进行光学图案化。我们展示了ZrO、TiO、HfO和ITO NPs的直接光学光刻，并研究了导致这种光致溶解度降低的化学和物理变化。微米厚的非晶ZrO NPs层以微米分辨率进行图案化，并显示出能够对可见光进行2π相位控制。我们还展示了多层图案化，并利用它来制造具有不同厚度和独特结构颜色的特征。在400°C退火后，沉积的ZrO结构在宽波长范围（0.3 - 10μm）内具有出色的光学透明度、高折射率（633nm时n = 1.84），并且光学表面光滑。然后，我们制造了诸如二元相位衍射光栅之类的衍射光学元件，它们表现出高效的衍射行为和良好的热稳定性。不同的氧化物NPs在图案化之前也可以混合，提供了高度的材料可调性。这项工作展示了一种通用的图案化方法，该方法利用了胶体氧化物纳米材料的可加工性和多样性，用于光子应用。
