Cho Himchan, Pan Jia-Ahn, Wu Haoqi, Lan Xinzheng, Coropceanu Igor, Wang Yuanyuan, Cho Wooje, Hill Ethan A, Anderson John S, Talapin Dmitri V
Department of Chemistry and James Franck Institute, University of Chicago, Chicago, IL, 60637, USA.
School of Optical and Electronic Information and Wuhan National Laboratory for Optoelectronics (WNLO), Huazhong University of Science and Technology, Wuhan, Hubei, 430074, P. R. China.
Adv Mater. 2020 Nov;32(46):e2003805. doi: 10.1002/adma.202003805. Epub 2020 Oct 1.
Precise patterning of quantum dot (QD) layers is an important prerequisite for fabricating QD light-emitting diode (QLED) displays and other optoelectronic devices. However, conventional patterning methods cannot simultaneously meet the stringent requirements of resolution, throughput, and uniformity of the pattern profile while maintaining a high photoluminescence quantum yield (PLQY) of the patterned QD layers. Here, a specially designed nanocrystal ink is introduced, "photopatternable emissive nanocrystals" (PENs), which satisfies these requirements. Photoacid generators in the PEN inks allow photoresist-free, high-resolution optical patterning of QDs through photochemical reactions and in situ ligand exchange in QD films. Various fluorescence and electroluminescence patterns with a feature size down to ≈1.5 µm are demonstrated using red, green, and blue PEN inks. The patterned QD films maintain ≈75% of original PLQY and the electroluminescence characteristics of the patterned QLEDs are comparable to thopse of non-patterned control devices. The patterning mechanism is elucidated by in-depth investigation of the photochemical transformations of the photoacid generators and changes in the optical properties of the QDs at each patterning step. This advanced patterning method provides a new way for additive manufacturing of integrated optoelectronic devices using colloidal QDs.
量子点（QD）层的精确图案化是制造量子点发光二极管（QLED）显示器和其他光电器件的重要前提。然而，传统的图案化方法在保持图案化量子点层的高光致发光量子产率（PLQY）的同时，无法同时满足分辨率、产量和图案轮廓均匀性的严格要求。在此，引入了一种经过特殊设计的纳米晶体墨水，即“可光图案化发光纳米晶体”（PEN），它满足了这些要求。PEN墨水中的光酸发生器通过光化学反应和量子点薄膜中的原位配体交换，实现了无光刻胶的量子点高分辨率光学图案化。使用红色、绿色和蓝色PEN墨水展示了各种特征尺寸低至≈1.5 µm的荧光和电致发光图案。图案化的量子点薄膜保持了约75%的原始PLQY，并且图案化QLED的电致发光特性与未图案化的对照器件相当。通过深入研究光酸发生器的光化学转变以及每个图案化步骤中量子点光学性质的变化，阐明了图案化机制。这种先进的图案化方法为使用胶体量子点的集成光电器件的增材制造提供了一种新途径。
