Organic light-emitting devices (OLEDs) have garnered significant research attention owing to their immense application prospects in leading technologies for full-color flat panel displays and eco-friendly solid-state lighting. They demonstrate exceptional features such as mercury-free construction, wide viewing angle, superior color quality and captivating flexibility. The requirements of light-emitting organic materials pertaining to high stability, lifetime and luminescence quantum yield, combined with the fabrication of devices with high performance efficiency, are highly challenging. Rational molecular design of 1,8-naphthalimide (NI) derivatives can offer quite promising results in achieving standard-light-emitting materials with a wide range of colors for OLED applications. This review is mainly focused on the synthesis and usage of varyingly substituted NI frameworks as luminescent host, dopant, hole-blocking and electron-transporting materials for OLEDs that emit not only red, orange, green and blue colors, but also function as white emitters, which can really have an impact on reducing the energy consumption. The future prospects that could be explored to improve the research in the highly promising field of OLEDs are also discussed.
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Optoelectronics is an active area of research and, for few decades, development of different semiconducting materials with a wide emission window has attracted researchers. Organic light emitting diodes (OLEDs) are primarily utilized in displays and light sources that greatly contribute towards the conservation of energy and do not need a backlight for displays. Development in device efficiency, lifetime and stability is now a major concern in this particular application, and designing efficient material for OLEDs has been an active field of research for decades. Metal-organic compounds possess different optical and electronic properties due to metal and organic ligand interactions which are primarily used in OLEDs. This review is mainly focused on the Schiff bases and their metal chelates as a pure emitting layer or as a dopant material for the fabrication of R/G/B/white emitting devices. Moreover, future prospects to explore further to advance research in the OLED arena are also discussed.
Graphic Abstract
There is always a need for efficient luminescent materials with simple synthesis and possible ease of hydrogen atom or functional group manipulation for use in different optoelectronic and biological applications. However, for certain real-world uses aggregation caused quenching effect of luminophores in their solid/aggregate state is undesirable, and is a cause of concern in areas, wherein the solid-state optical performance is more crucial. In this regard, chalcones have been explored for their ability to display aggregation-induced emission (AIE) or aggregation-induced enhanced emission (AIEE), which can be of practical use. This article is thus focused on an integrated evidence-based report on the AIE/AIEE-active chalcone systems for potential technological and biological applications.
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Mild steel (MS) is one among the extensively utilized materials in several industrial sectors, but prone to deterioration when exposed to acidic environment. The main focus of this study is to examine the corrosion inhibitive efficacy of 9-ethyl-3-carbazolecarboxaldehyde azine (CCA) on MS immersed in 0.5 M HCl medium. The corrosion inhibition efficiency of CCA which was investigated using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) techniques improved with rise in temperature and inhibitor concentration. CCA showed a maximum inhibition efficiency of 92.4% at 323 K for 5 × 10–5 M concentration in 0.5 M HCl medium. The variation in the kinetic and thermodynamic parameters indicated chemisorption of CCA on MS, and its mixed-type inhibitive action followed Langmuir’s isotherm model. The infrared spectra provided evidences for the chemical interaction of CCA with MS specimen. Surface morphology evaluation using SEM and AFM in combination with elemental analysis using an energy dispersive X-ray analyser (EDX) indicated the creation of a protective adsorption layer of CCA on MS surface. The quantum chemical investigations performed using density functional theory (DFT) computations supplemented the experimental results, suggesting the potential corrosion inhibition behavior of CCA toward MS in aggressive HCl medium.
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The deterioration of iron-based alloys, especially mild steel (MS) is one amongst the most challenging problems faced in various chemical industries. The present work focuses on the potential activity of a naphthalimide derivative namely 2-(2-hydroxyethyl)benzo[de]isoquinoline-1,3-dione (HBIQ) as corrosion inhibitor for MS in sulfamic acid (SA) medium in the temperature range from 303 to 323 K. Potentiodynamic polarization (PP) and electrochemical impedance spectroscopy (EIS) were employed in the experimental measurement and HBIQ exhibited 89% inhibition at its optimum concentration. HBIQ demonstrated electrostatic interactions with MS surface and behaved as a mixed type of inhibitor by obeying Langmuir’s isotherm model. Surface characterization of uninhibited and inhibited MS specimens combined with elemental analysis data provided clear evidences for the formation of a protective adsorption layer of HBIQ on MS surface. Spectral analysis such as Ultraviolet visible and Fourier Transform Infra-red spectral analyses were carried out in order to confirm the adsorption of HBIQ on to the metal surface. The density functional theory calculations supported the experimental results and indicated the contribution of delocalized π-electrons in the naphthalimide unit and the lone-pair electrons of oxygen in the carbonyl and hydroxyl group for improved adsorption of HBIQ onto MS surface, thereby reducing the corrosion of the alloy in SA environment.
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