Breaking the Ultraviolet Lithography Limit to Achieve Submicron Quantum Dot Light-Emitting Array Devices

Direct photolithography is a feasible patterning technique that facilitates the creation of ultrafine full-color quantum dot (QD) arrays. However, the lithographic pixel size is primarily limited by the wavelength of ultraviolet (UV) light passing through the photomask. Here, we report an ingenious patterning strategy for circumventing pixel resolution limitations via a maskless photolithography, which can readily produce uniform submicrometer patterns (0.5 μm using a 365 nm UV light). Monolayer photo-cross-linkers are nanoimprinted onto the QD layer to bridge the surface ligands between adjacent QDs under UV irradiation, thereby generating stable QD patterns after developing. More importantly, the molecularly thick photo-cross-linker weakens the electron injection ability and reduces the interface exciton quenching to improve the fluorescence lifetime. We have successfully fabricated high-performance QD light-emitting diodes (QLEDs) with a resolution of 25,400 pixels per inch. This study expands the toolbox for overcoming the diffraction limit of photolithography to achieve ultrahigh resolution QLEDs.