Photosensitizer-assisted direct 2D patterning and 3D printing of colloidal quantum dots

Direct photopatterning is a powerful strategy for patterning colloidal quantum dots(QDs)for their integration in various electronic and optoelectronic devices.However,ultraviolet(UV)exposure required for QD patterning,especially those with short wavelength(e.g.,deep UV light),can degrade the photo-,and electroluminescence,and other properties of patterned QDs.Here we develop a photosensitizer-assisted approach for direct photopatterning of QDs with h-line(centered at 405 nm)UV light and better preservation of their luminescent properties.This approach uses a photosensitizer that can absorb the h-line UV light and transfer the energy to activate bisazide-based crosslinkers via Dexter energy transfer.Uniform,high-resolution(smallest feature size,2μm),and full-color patterns of red,green,and blue QD layers can be achieved.The patterned QD layers maintain up to~90%of their original photoluminescent quantum yields,comparing favorably with those(<60%)of QDs patterned without photosensitizers.We further extended the strategy to the direct three-dimensional(3D)printing of QDs.This photosensitizerassisted approach offers a new way for direct two-dimensional(2D)photopatterning and 3D printing of colloidal QDs,with implications in building high-performance QD optoelectronic devices.