Ligand-Engineered Direct Optical Lithography of Nanocrystals with Industrially Compatible Solvents

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.