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, 2 µm), 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 photosensitizer-assisted 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.