Pulsed Laser Photopatterning of Cesium Lead Halide Perovskite Structures as Robust Solution-Processed Optical Gain Media

Solution-processed optical gain media such as thin films of colloidal semiconductor nanocrystals promise ease of fabrication and scalable production while offering a spectrally wide range of emission colors. However, depositing such gain media in a size- and shape-specific manner at a precise location on a substrate can be highly challenging. In this work, a facile approach for fabricating solution-processed cesium lead halide perovskite structures of any arbitrary shape and size from their nanocrystal counterparts via a pulsed laser photopatterning process is demonstrated. The photopatterned structures resist solvation in both polar and nonpolar solvents, allowing for the straightforward removal of unpatterned regions. Their robustness is attributed to the ligand-removal, sintering, and photoannealing of the nanocrystals at the site of irradiation. Concomittantly, the photopatterning process results in lengthened Auger-dominated biexciton lifetimes and larger absorption cross-sections that permit relatively low amplified spontaneous emission thresholds. It is shown that the photopatterning process may be used to fabricate cesium lead halide based gain media capable of multiwavelength emission, orientation-dependent wavelength of emission, as well as functional operation while fully immersed in various solvents. It is envisioned that the photopatterning process may be extended to other perovskite systems to include applications beyond those requiring light-emission.