Controlling Green-to-Blue Luminescence in Multidimensional ZnO Interfaces: Mechanistic Insights

Abstract

This report presents a thorough study on controlling the morphological and optical properties of zinc oxide nanostructured coatings (n-ZnO) using the vapor-phase growth technique with metallic catalysts on silicon substrates. A successful control over the morphological characteristics of the n-ZnO materials, yielding a mixed one-dimensional (1D)–two-dimensional (2D) matrix through simultaneous competing vapor–liquid–solid (VLS) and vapor–solid–solid (VSS) growth mechanisms, was shown. The obtained 1DZnO nanostructured materials exhibited a diameter of 112 nm and a length of 3.7 μm (i.e., nanowires) along with 2DZnO nanomaterials with a surface area of 2.6 μm2 (i.e., nanowalls) in average. The investigation also emphasizes the influence of the Zn-gas precursor gradient on the structures’ morphology, yielding a variation in the 2DZnO surface area from 11.8 to 0.5 μm2 as the distance between the evaporation source and the substrate increased from 27 to 324 mm. Furthermore, a defect engineering process involving thermal treatments in hydrogen, oxygen, and nitrogen atmospheres is used to tune the visible photoluminescence response of the material from a 526 to a 400 nm emission. This approach enables control over multiple recombination centers (i.e., oxygen and zinc interstitials and vacancies), modifying the optical properties of the n-ZnO. The study reveals a reversible, controllable, and reproducible transition between near-band-edge (NBE) and deep-level emission (DLE). As a perspective, laser ablation treatments were also used to modulate the photoluminescence and morphological properties. We found that n-ZnO visible emission was blue-shifted when irradiating with 5–21 mJ laser energy. The findings suggest that this capability holds exciting potential for developing advanced nanostructures on contemporary technologies, such as lighting and sensing, where the continuous search for an efficient and cost-effective blue emitter is necessary.

Sputtering Deposition of ZnO Thin Films for Photocatalytic Hydrogen Production: Perspectives on Upscaling

“…Nevertheless, through the spectrum fitting process for the z03 sample, additional centers contributing to the material's emission were identified. In this instance, the sample exhibits centers at 2.65 eV and 2.17 eV, which have been previously attributed in reports to extended zinc interstitials (ex-Zni) (Galdámez-Martínez et al, 2023) and VOZni (Alvi et al, 2010) complex, respectively. Although the unequivocal assignment of these defects remains a subject of ongoing debate in the literature (Wang et al, 2018), the assertion that a higher abundance of defects is associated with the emission of the thinner ZnO films synthesized in this study is compelling.…”

Anticipating Challenges in Optical Nanobiosensors for Global Detection of Respiratory Viruses and Emerging Threats

“…71 In addition, the reversible tuning of ZnO nanowires' photoluminescence from green to blue offers properties like high surface-to-volume ratio and sensitivity to environmental changes for the improvement of optical biosensing platforms, as demonstrated by Galdamez et al, which could be aimed at detecting airborne diseases. 72 Interaction with pathogens induces shifts in photoluminescent emission, enabling real-time, labelfree detection. 70 This reversibility ensures platform sustainability and the green-to-blue transition adds versatility for further multiplexed configurations.…”

A highly efficient deep red-emitting Mn4+-powered oxyfluoride nanophosphor developed for plant growth and optical thermometric applications

“…Therefore, the demand for nanophosphors for nanodevice applications is growing. [20][21][22][23][24] Eventually, a scalable synthesis approach for making nanosized phosphors is indeed very crucial for implementing the developed product in many nano-level devices. 12,13,[17][18][19] The luminescence centers of Mn 4+ ions can be simply produced by high-temperature solid-state calcination in air.…”

“…Therefore, the demand for nanophosphors for nanodevice applications is growing. 20–24 Eventually, a scalable synthesis approach for making nanosized phosphors is indeed very crucial for implementing the developed product in many nano-level devices. 12,13,17–19…”