Versatile Solution‐Processed Organic–Inorganic Hybrid Superlattices for Ultraflexible and Transparent High‐Performance Optoelectronic Devices

Abstract

Crystalline or amorphous metal oxides are widely used in various optoelectronic devices as key components, such as transparent conductive electrodes, dielectrics or semiconducting active layers for thin-film transistor (TFT) backplanes in large-area displays, photovoltaics, and light-emitting diodes. Although crystalline inorganic materials demonstrate outstanding optoelectronic performance, owing to their wide bandgaps, large conductivities, and high carrier mobilities, their inherent brittleness makes them vulnerable to mechanical stress, thereby limiting the use of metal-oxide films in emerging flexible electronic applications. In this study, stress-diffusive organicinorganic hybrid superlattice nanostructures are developed to overcome the mechanical limitation of crystalline oxides and to provide high mechanical stability to metal-oxide semiconductors. In particular, hybrid transparent superlattice electrodes based on crystalline indium-tin oxide exhibit high electrical conductivities of up to 555 S cm -1 (resistance variation < 3%) and effectively reduce the mechanical stress on the inorganic layer (up to 10 000 bending cycles with a radius of 1 mm). Furthermore, to ensure the viability of the hybrid superlattice flexible electronics, all solution-processed superlattice crystalline indium-gallium-oxide TFTs are implemented on a thin (≈5 µm) polyimide substrate, providing highly robust and excellent electrical performance (average mobility of 7.6 cm 2 V -1 s -1 ).

Enabling three-dimensional porous architectures via carbonyl functionalization and molecular-specific organic-SERS platforms

“…Their ability to form nano-/micro-structured thin-films from solution or vapor phase with tunable morphologies and optoelectronic properties has greatly benefited the research for next-generation optoelectronic devices 10 – 12 . Although most of these device technologies, such as organic field-effect transistors (OFETs) 13 – 15 or light-emitting diodes 16 , have now become a conventional application avenue for molecular semiconductors, they hold huge promise also for unconventional applications such as surface-enhanced Raman spectroscopy (SERS). As we have recently disclosed in our pioneering studies 17 , 18 , the nanostructured organic films of π-electron-deficient fluorinated oligothiophene semiconductors DFH-4T 17 and DFP-4T 18 , fabricated via physical vapor deposition (PVD), enabled the Raman detection of organic analytes (e.g., methylene blue (MB) and rhodamine 6 G) without needing a metallic or an inorganic layer.…”

Super-flexibility in Freestanding Single-Crystal SrRuO3 Conductive Oxide Membranes

“…Materials with flexibility and high electrical conductivity are critical for flexible electronics. − Although organic materials are naturally flexible, their electrical conductivity, thermal stability, and mechanical processing properties are relatively poor, making it difficult to meet the development requirements of flexible electronic devices. − Compared with organic materials, inorganic materials have good electrical conductivity and compatibility with other semiconductor materials − but are generally brittle because of their inherent strong ionic bonds, which limits their applications to flexible electronic devices. − In order to expand the application of inorganic oxide thin films in flexible electronic devices, researchers usually deposit oxide films on flexible substrates like mica and polymer substrates to achieve small deformations. − Recently, a method of etching the sacrificial layer to fabricate freestanding membranes was developed, which completely frees the inorganic oxide film from the constraints of the substrate and achieves flexibility comparable to that of two-dimensional materials. − The flexibility of a material is essentially determined by its mechanical properties, such as Young’s modulus, and related research is very helpful for the application of flexible electronic devices. Here, freestanding conductive oxide membranes with super-flexibility were prepared, and the mechanical properties were discussed.…”

O2 and H2O Barrier-Based High Reliability and Stability Using Polytetrafluoroethylene Passivation Layer for Solution Processed Indium Oxide Thin Film Transistors

“…However, the reliability issues, instability of bias stress [14], and inherent brittleness of the inorganic material [15] put a limit on the development of a durable active layer and bendable/flexible electronics. And the poor electrical performance of In 2 O 3 TFTs at the annealing temperature around 200 • C was noticed as a restriction for practical applications [16]- [18].…”