Photopatterning of Perovskite Nanocrystals with Photo-Crosslinkable Ligands

Perovskite nanocrystals (NCs) have emerged as promising luminescent materials for full-colour display applications due to their strong optical properties, widely tunable emission, and narrow full-width half maximum. By precise tuning of their emission spectra, high-resolution full-colour light-emitting diode (LED) arrays can be achieved by micro-patterning red, green, and blue sub-pixels with perovskite NCs as emitters. Currently, photolithography is the most widely used patterning technique in the industry due to its capabilities to achieve high resolution, large area production, and low cost. However, due to the ionic nature of perovskite NCs, conventional photolithography techniques are incompatible as the use of polar solvents can damage underlying perovskite NC patterns, resulting in defect formation and luminescence quenching. Herein, we report a series of novel photo-crosslinkable ligands for the microscale patterning of perovskite NCs. We incorporated photosensitive acrylate groups in the ligands, which upon exposure to ultraviolet light, undergo polymerization and changes the solubility of the NC films. This enables the direct photo-patterning of perovskite NCs without the need for additional photoresist. Through a facile solution-phase ligand exchange process, we functionalized cesium lead halide (CsPbX₃) NCs with our photo-crosslinkable ligands. We also demonstrate the photopatterning of 10 µm features on the CsPbX₃ NC films via direct laser writing with a 405 nm laser. Our approach offers a versatile strategy for the patterning of perovskite NC films in a simple and cost-effective manner, thus enabling the integration of perovskite NCs in various display applications.