Theoretical insight into a series of cyclometalated platinum(II) complexes with the substituted 2-phenylimidazole ligand

<p>The photophysical properties of a series of platinum(II) complexes have been theoretically investigated. The effect of the electron-withdrawing and electron-donating substituents on charge injection, transport, absorption and phosphorescent properties has been studied. For complexes <b>1</b>–<b>5</b>, the phosphorescence at 474, 453, 451, 524 and 461 nm are assigned to ³MLCT(triplet metal-to-ligand charge transfer)/³ILCT(triplet intraligand charge transfer). In addition, ionization potential (IP), electron affinities (EA) and reorganization energy have also been analyzed to evaluate the charge transfer and balance properties between hole and electron. The calculated results show the complex <b>2</b> possibly possesses the largest radiative decay rate value among these studied complexes.</p

DFT/TDDFT investigation on the photophysical properties of a series of phosphorescent cyclometalated complexes based on the benchmark complex FIrpic

<p>The photophysical properties of four Ir(III) complexes have been investigated by means of the density functional theory/time-dependent density functional theory (DFT/TDDFT). The effect of the electron-withdrawing and electron-donating substituents on charge injection, transport, absorption and phosphorescent properties has been studied. The theoretical calculation shows that the lowest-lying singlet absorptions for complexes <b>1</b>–<b>4</b> are located at 387, 385, 418 and 386 nm, respectively. For <b>1</b>–<b>4</b>, the phosphorescence at 465, 485, 494 and 478 nm is mainly attributed to the LUMO → HOMO and LUMO → HOMO-1 transition configurations characteristics. In addition, ionisation potential (IP), electron affinities (EAs) and reorganisation energy have been investigated to evaluate the charge transfer and balance properties between hole and electron. The balance of the reorganisation energies for complex <b>3</b> is better than others. The difference between hole transport and electron transport for complex <b>3</b> is the smallest among these complexes, which is beneficial to achieve the hole and electron transfer balance in emitting layer.</p

<i>A</i>‑Site-Doping Enhanced <i>B</i>‑Site Ordering and Correlated Magnetic Property in La_2–<i>x</i>Bi_<i>x</i>CoMnO₆

A series of Bi-doped La_2–<i>x</i>Bi_<i>x</i>CoMnO₆ double perovskite oxides are synthesized, and the impact of doping on crystal structures and magnetic properties is investigated comprehensively. X-ray photoelectron spectroscopy and Raman spectrum analyses reveal that ordering of Co and Mn ions at <i>B</i>-site is gradually improved with the rise of Bi concentration. Meanwhile, magnetic disordering is suppressed greatly by showing larger magnetic moments. Structurally, the Rietveld refinement shows that the bonds are elongated, while the bond angles are shrunken after doping, giving rise to lowered Curie temperature. We also observe a large negative zero-field-cooling magnetization, which is attributed to the formation of spin antiparallel or canted ferromagnetic domains and clusters that are separated by the antiphase boundaries. First-principles calculations confirm the enhanced Co–Mn ordering upon Bi doping by taking into account both the ordering and disordering configurations of La₂CoMnO₆, LaBiCoMnO₆, and Bi₂CoMnO₆. Moreover, we find a spin-state transition in the antisite Co ions from high-spin (Co²⁺-t_2g⁵e_g²) to low-spin state (Co³⁺-t_2g⁶e_g⁰), which is consistent with the increased total magnetic moments by the Bi doping