DOI: 10.25442/hku.29413835
title: Supporting data for “3d nano-printing of layered halide perovskite heterostructures”

description: Layered halide perovskites (LHPs) have garnered substantial interest as promising candidates for advanced optoelectronic applications, including solar cells, light-emitting diodes, lasers, and photodetectors, due to their tunable bandgaps, exceptional absorption coefficients, and compatibility with low-cost, solution-based fabrication methods. However, conventional thin-film deposition techniques significantly restrict structural complexity and compositional versatility, hindering the development of intricate three-dimensional (3D) device architectures. To address these challenges, this dissertation presents a novel meniscus-guided 3D nano-printing platform specifically developed for fabricating vertically aligned LHP nanowires and heterostructures with unprecedented precision, scalability, and compositional flexibility.This innovative meniscus-guided 3D nano-printing technique leverages a femtoliter-scale meniscus formed at the tip of a nanopipette to precisely direct localized crystallization processes. This approach enables deterministic growth of freestanding nanowires with finely controlled dimensions, compositions, and orientations. By systematically optimizing essential printing parameters, such as pulling speed, ink formulation, and substrate temperature, the method achieves highly reproducible arrays of vertically oriented, high-aspect-ratio LHP nanowires exhibiting outstanding crystallinity and uniformity. Demonstrations include successful fabrication of both Ruddlesden–Popper(RP) and Dion–Jacobson(DJ) perovskites, significantly expanding the range of potential optoelectronic applications. Comprehensive electronic characterization, including detailed current–voltage analyses under various illumination wavelengths, further highlights the capability of the printed LHP nanowires as high-speed, broadband photodetectors. Integrated photodetector devices fabricated from these nanowire arrays demonstrate rapid photo-switching responses, superior on/off current ratios, and consistent operational stability, emphasizing the practical applicability and transformative potential of this novel fabrication strategy.Extending these technological breakthroughs, the dissertation introduces the first successful fabrication of multi-segmented LHP nanowire heterostructure s through the meniscus-guided 3D nano-printing technique. This advanced printing method allows for on-demand, lithography-free integration of nanowire heterostructures with customizable geometries and precise compositional profiles. Through detailed photoluminescence mapping and theoretical modeling, the study investigates diffusion kinetics of halide anions within printed heterostructures, confirming significantly enhanced moisture resistance and suppressed ion diffusion. These attributes render the fabricated nanowire heterostructures exceptionally suitable for optoelectronic applications demanding long-term stability and durability.In summary, this dissertation firmly establishes meniscus-guided 3D nano-printing as a versatile, robust, and powerful platform for constructing sophisticated LHP nanostructures and their heterostructures. By enabling direct-write capabilities, superior compositional flexibility, and enhanced environmental resilience, this innovative technique bridges fundamental materials science discoveries with practical optoelectronic applications. Beyond photodetection, the methodologies and insights developed herein hold broad potential for implementation in solar cells, LEDs, lasers, sensors, and next-generation integrated photonic systems, laying crucial groundwork for future advancements in high-performance, LHP-based optoelectronics.