Van der Waals Epitaxy of Thin Gold Films on 2D Material Surfaces for Transparent Electrodes: All-Solution-Processed Quantum Dot Light-Emitting Diodes on Flexible Substrates

Abstract

With the assistance of van der Waals (vdW) epitaxy, nanometer-thick and highly conductive gold films are deposited onto MoS 2 surfaces for use as transparent anode electrodes in quantum dot light-emitting diodes (QLEDs) on poly(ethylene terephthalate) (PET) substrates. After transferring wafer-scale and monolayer MoS 2 to PET substrates, 10 nm thick gold (Au) films are deposited onto the two-dimensional (2D) material surfaces as anode electrodes. Bounded only by weak vdW forces on 2D material surfaces, the diffusive Au adatoms tend to facilitate lateral growth and lead to the formation of continuous and highly conductive thin metal films in the nanometer regime. The Au film exhibits excellent tensile bending stability for its sheet resistance, which is superior to that of rigid indium−tin oxide (ITO) films on PET substrates. Thermally stable CdSe@CdZnS/ZnS QLEDs are fabricated on the PET substrate. Compared with devices fabricated on sapphire substrates, the phenomenon of sub-bandgap turn-on is observed for the flexible device. Based on our demonstrations, the high conductivity and robust durability toward substrate bending make the nanometer-thick Au film grown on 2D material surfaces a promising candidate to replace current ITO anode electrodes for flexible device applications.

Flexible Double-Side Red Emission Quantum Dot Light-Emitting Diodes via van der Waals Epitaxy of Nanometer-Thick Metal Transparent Electrodes on Two-Dimensional MoS2

“…The cross section of the Au anode and Al strips defined the device active area of 2 × 2 mm 2 . The following device measurements were performed in the glovebox, after the DSE-QLEDs were postmetallization annealed at 120 °C …”

“…9,10 With high conductivity, transparency, and bending flexibility, the vdW epitaxial thin metal films become a promising candidate to replace the awkward indium−tin-oxide (ITO) transparent electrode in flexible optoelectronic devices. 14 out-of-plane A 1g vibrational modes of MoS 2 is generally adopted as a nondestructive measurement to verify the layer numbers of MoS 2 films. 15 As shown, the energy difference (Δk) of MoS 2 on sapphire is approximately 20.2 cm −1 with a distinct E 2g 1 /A 1g intensity ratio of 1.6, which suggests the formation of a monolayer MoS 2 .…”

“…For the 2D transition-metal dichalcogenides (TMDs), MoS 2 is the most successful material for its large area and layer-controllable growth without structural defects . As a result, it has been well-demonstrated that a continuous metal film with very low sheet resistance covering across the large-area 2D MoS 2 can be achieved with film thicknesses of only a few nanometers. , With high conductivity, transparency, and bending flexibility, the vdW epitaxial thin metal films become a promising candidate to replace the awkward indium–tin-oxide (ITO) transparent electrode in flexible optoelectronic devices . In this study, MoS 2 -mediated vdW-epitaxial thin metal films were deposited for both the transparent Au anode and Al cathode, as shown in Scheme .…”

The energetic and physical concept of gold nanorod-dependent fluorescence in cancer treatment and development of new photonic compounds|review

“…13,[17][18][19] In summary, combining (GNR) and QDs offers a versatile hybrid system with enhanced optical features and potential imaging, sensing, and theragnostic uses. The integration of the unique plasmonic feature of (GNR) with the tunable emission feature of QDs provides opportunities for advanced imaging, sensitive detection, and multifunctional platforms for biomedical uses 17,20,21 and colloidal (G) nanoparticles, including (GNR), have found diverse uses in various elds. Their distinct optical feature makes them valuable in biomedical imaging, where they can play as contrast agents for techniques like dark-eld microscopy, electron microscopy, or surface-enhanced Raman spectroscopy (SERS).…”

“…Additionally, the colloidal (GNP) surface may be functionalized with biomolecules, like antibodies or aptamers, allowing for related targeting and recognition in biosensing uses. 20,[22][23][24][25] The adaptability and versatility of GNP in cancer treatment have led to advancements in targeted therapies, imaging techniques, and multimodal approaches. Ongoing research continues to explore the potential of GNP in improving cancer treatment outcomes and developing novel therapeutic strategies.…”