Ligand-Engineered Direct Optical Lithography of Nanocrystals with Industrially Compatible Solvents
Pengwei Xiao, Jianchao Ma, Zhoufan Zhang, Yihao Zou, Huanhuan Luo, Jie Guan, Jianrong Zhang, Likuan Zhou, Wenjun Hou, Panke Zhang, Dmitri V. Talapin, Yuanyuan Wang
Abstract
Nondestructive and precise patterning of colloidal semiconductor nanocrystals (NCs) is critical in the fabrication of solution-processable optoelectronic devices. Direct optical lithography of functional inorganic nanomaterials (DOLFIN) is widely used for the high-resolution patterning of NCs. However, conventional DOLFIN chemistry relies on solvents incompatible with mainstream industrial lithography processes, which impedes DOLFN's widespread adoption as a universal technology for real-world additive manufacturing. In this work, we proposed specific criteria for ligand design and designed a series of multifunctional ligands combining methacrylate and carboxyl groups. Such ligands allowed us to colloidally stabilize and optically pattern NCs with i-line and h-line light sources by using industrially friendly solvents. We showed that single-color and multicolor patterns with a spatial resolution of 1 μm can be achieved without compromising the optical and optoelectronic properties. The patterned NC films showed photoluminescence (PL) and electroluminescence (EL) on par with those of unpatterned films. The red-emitting QLEDs showed a peak external quantum efficiency (EQE) of 22.0%. The ability to reliably pattern bright NCs from PGMEA will facilitate the adoption of DOLFIN as an industrialized system-level integration platform and will significantly impact the production of high-resolution, full-color QLED devices.