Solvent-Annealing Assisted 3D Printing of High-Performance, Freestanding Perovskite Nanolasers

Inorganic metal halide perovskites are emerging as promising optoelectronic materials due to their strong, tunable, and high-color-purity photo- and electroluminescence, and solution processability^1–3. Recently, extensive research has been made to utilize perovskite nanowires as lasers due to their structural benefits such as ultra-compact sizes, highly localized coherent output, and efficient waveguiding^4,5. The current fabrication of perovskite nanowires relies on electron beam lithography, photolithography, chemical vapor deposition, solution-phase synthesis, and nanoimprinting. That is to say, these processes are energy- and labor-intensive, which is in stark contrast with the industrial low-cost requirements. Furthermore, technological challenges associated with individual tailoring of nanowire geometries remain unresolved, making it difficult to manipulate stimulated emission characteristics at the single nanowire level. A new method that can fabricate perovskite nanowires with programmed shape, dimension, and placement is in great demand for addressing the abovementioned issue.<br/><br/>Here, we demonstrate an electrohydrodynamic (EHD) 3D printing of perovskite nanowires for high-performance bespoke lasers. The printed perovskite nanowire presents a two-photon pumped Fabry–Pérot (FP) mode lasing. By adjusting the height of a freestanding nanowire at will, we are able to select the lasing mode and also control the lasing threshold and mode spacing (△λ). On this basis, we successfully demonstrated the 3D printed nanowires arrays for multi-level anti-counterfeiting security labels by storing information in the cavity-height-dependent features such as the lasing threshold and mode spacing (△λ), which are unclonable. More importantly, solvent annealing was exploited to increase the grain size and crystallinity by promoting recrystallization in the printed nanowire. As a result, the lasing threshold was drastically improved from 25 µJ/cm² to 3 µJ/cm², which is the leading record for CsPbBr₃ FP lasers. It is also worth mentioning that the advanced features of our technique such as maskless operation and low-cost production with high stability make it an effective platform to bring the proof-of-concept demonstration into practical commercial application. Likewise, these outcomes not only give us inspiration for the function-oriented design of the nanolaser-based devices but also facilitate the development of high-performance perovskite-based photonic anti-counterfeiting applications. Last but not least, our method could provide an excellent platform to construct scalable, on-demand laser-based photonic devices.<br/><br/>1. Stranks, S. D. <i>et al.</i> Electron-hole diffusion lengths exceeding 1 micrometer in an organometal trihalide perovskite absorber. <i>Science (80-. ).</i> <b>342</b>, 341–344 (2013).<br/>2. Braly, I. L. <i>et al.</i> Hybrid perovskite films approaching the radiative limit with over 90% photoluminescence quantum efficiency. <i>Nat. Photonics 2018 126</i> <b>12</b>, 355–361 (2018).<br/>3. Lin, K. <i>et al.</i> Perovskite light-emitting diodes with external quantum efficiency exceeding 20 percent. <i>Nat. 2018 5627726</i> <b>562</b>, 245–248 (2018).<br/>4. Chen, M. <i>et al.</i> 3D Nanoprinting of Perovskites. <i>Adv. Mater.</i> <b>31</b>, 1–8 (2019).<br/>5. Chen, M. <i>et al.</i> Three-Dimensional Perovskite Nanopixels for Ultrahigh-Resolution Color Displays and Multilevel Anticounterfeiting. <i>Nano Lett.</i> <b>21</b>, 5186–5194 (2021).