Department of Chemistry and James Franck Institute, Chicago, Illinois 60637, United States.
School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, P. R. China.
J Am Chem Soc. 2022 Jun 15;144(23):10495-10506. doi: 10.1021/jacs.2c03672. Epub 2022 Jun 9.
Patterning functional inorganic nanomaterials is an important process for advanced manufacturing of quantum dot (QD) electronic and optoelectronic devices. This is typically achieved by inkjet printing, microcontact printing, and photo- and e-beam lithography. Here, we investigate a different patterning approach that utilizes local heating, which can be generated by various sources, such as UV-, visible-, and IR-illumination, or by proximity heat transfer. This direct thermal lithography method, termed here heat-induced patterning of inorganic nanomaterials (HIPIN), uses colloidal nanomaterials with thermally unstable surface ligands. We designed several families of such ligands and investigated their chemical and physical transformations responsible for heat-induced changes of nanocrystal solubility. Compared to traditional photolithography using photochemical surface reactions, HIPIN extends the scope of direct optical lithography toward longer wavelengths of visible (532 nm) and infrared (10.6 μm) radiation, which is necessary for patterning optically thick layers (e.g., 1.2 μm) of light-absorbing nanomaterials. HIPIN enables patterning of features defined by the diffraction-limited beam size. Our approach can be used for direct patterning of metal, semiconductor, and dielectric nanomaterials. Patterned semiconductor QDs retain the majority of their as-synthesized photoluminescence quantum yield. This work demonstrates the generality of thermal patterning of nanomaterials and provides a new path for additive device manufacturing using diverse colloidal nanoscale building blocks.
功能无机纳米材料的图案化是先进量子点（QD）电子和光电设备制造的重要过程。这通常通过喷墨打印、微接触印刷、光和电子束光刻来实现。在这里，我们研究了一种不同的图案化方法，该方法利用各种来源（如 UV、可见和 IR 照射或近场热传递）产生的局部加热。这种直接热光刻方法称为无机纳米材料的热诱导图案化（HIPIN），它使用具有热不稳定表面配体的胶体纳米材料。我们设计了几类这样的配体，并研究了它们的化学和物理变化，这些变化负责纳米晶溶解度的热诱导变化。与使用光化学反应的传统光刻相比，HIPIN 将直接光学光刻的范围扩展到更长的可见光（532nm）和红外（10.6μm）辐射波长，这对于图案化光吸收纳米材料的光学厚层（例如 1.2μm）是必要的。HIPIN 能够对由衍射极限光束尺寸定义的特征进行图案化。我们的方法可用于直接图案化金属、半导体和介电纳米材料。图案化的半导体 QD 保留了其大部分合成时的光致发光量子产率。这项工作证明了纳米材料热图案化的普遍性，并为使用各种胶体纳米级构建块进行添加剂器件制造提供了新途径。
