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, 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 proximity heat transfer. This direct thermal lithography method, termed here as Heat-Induced Patterning of Inorganic Nanomaterials (HIPIN), uses colloidal nanomaterials with thermally decomposable surface ligands. We designed several families of thermally decomposable surface ligands and investigated the 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. Moreover, HIPIN enables pattern features smaller than the diffraction-limited beam size. Our approach can be used for direct patterning of metal, semiconductor and dielectric nanomaterials. Patterned semiconductor QDs retain majority of their original photoluminescence quantum yield. This work demonstrates generality of thermal patterning of nanomaterials and provides a new path for additive device manufacturing using diverse colloidal nanoscale building blocks.

Direct heat-induced patterning of inorganic nanomaterials

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