Today organic light emitting diodes are a topic of significant academic and industrial research interest. OLED technology is used in commercially available displays, and efforts have been directed to improve this technology. Design and synthesis of phosphorescent based transition metals are capable of harvesting both singlet and triplet excitons and achieve 100 % internal quantum efficiency is an active area of research. Among all the transition metals, iridium is considered a prime candidate for OLEDs due to its prominent photophysical characteristics. In the present review, we have concentrated on the Iridium based homo and heteroleptic complexes that have dissimilar substitutions on phenylpyridine ligands, different ancillary ligands and the effect of substitution on HOMO/LUMO energies and a brief discussion and correlation on the photophysical, electrochemical and device performances of the different complexes have been reviewed for organic light emitting diodes.

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We describe a systematic study of the influence of halides and solvents on the optical properties of EuII-containing complexes in solution starting from well-defined crystalline precursors. Anionic halides, chloride and bromide, blue-shift the spectroscopic properties of EuII, whereas neutral ligands, methanol and acetonitrile, cause a red shift. This system provides evidence that EuII has a stronger affinity for chloride, and to some extent bromide, relative to acetonitrile but not methanol. We also describe a simple procedure using an ion-exchange resin for the exchange of iodide counterions to hexafluorophosphate. These findings are a step toward designing ligands that can tune the optical properties of EuII-containing complexes for solution-based applications.

Six novel yellowish-orange light emitting dye molecules consisting of an electron deficient phenone (acceptor) linked to triphenylamine (donor), were designed and synthesized. The photophysical and electrochemical properties of the dyes were systematically investigated and examined using DFT calculations. All the synthesized dye materials have shown high quantum yields (ranging from 0.35to0.74%). The dyes emitted intense yellowish-orange (x = 0.427, y = 0.481) to orange color (x = 0.511, y = 0.484) with appropriate CIE color coordinates. The synthesised dyes were used for generating white light by fabricating white LEDs. Among all hybrid white LED devices TPA-2 has shown bright white emission with CIE color coordinates x = 0.32, y = 0.33. Theoretical calculations have been performed to explore the optical, electronic, charge transport, and stability properties of the TPA derivatives as charge transport and emissive materials for organic light emitting devices (OLEDs). The results show that, all the derivatives are highly luminescent and their hole transport performances are more favourable than their electron transport performances. So these materials can be used as hole transport materials for OLEDs.

We have designed and synthesized donor (D) and acceptor (A) phosphors [D and A refer to the electron-donating and electron-withdrawing moieties, respectively] as yellow-emitting organic phosphors.