Synthesis and photophysical properties of the highly emissive complex [Ir(Fppy)2(dmb)](+) are reported along with those of additional heteroleptic cyclometalated Ir(III) complexes, [Ir(ppy)2(NN)](PF6): FppyH = 2-(2,4-difluorophenyl)pyridine; ppyH = 2-phenylpyridine; NN = 4,4'-dimethyl-2,2'-bipyridine (dmb), 1,10-phenanthroline (phen), or 4,7-diphenyl-1,10-phenanthroline (Ph2phen). TD-DFT calculations and Franck-Condon emission spectral band shape analyses show that the broad and structureless emission from [Ir(Fppy)2(dmb)](+) in acetonitrile at 298 K mainly arises from a triplet metal-to-ligand charge-transfer excited state, (3)MLCTIr(ppy)→NN. The emission maximum varies systematically with variations in electron-donating or -withdrawing substituents on both the NN and the Xppy ligands, and emission efficiencies are high, with an impressive ϕ ≈ 1 for [Ir(Fppy)2(dmb)](+). At 77 K in propionitrile/butyronitrile (4/5, v/v), emission from [Ir(Fppy)2(dmb)](+) is narrow and highly structured consistent with a triplet ligand-centered transition ((3)LCNN) and an inversion in excited-state ordering between the (3)MLCTIr(ppy)→NN and (3)LCNN states. In a semirigid film of the poly(ethyleneglycol)dimethacrylate with nine ethylene glycol spacers, PEG-DMA550, emission from [Ir(Fppy)2(dmb)](+) is MLCT-based. The thermal sensitivity of the photophysical properties of this excited state points to a possible application as a temperature sensor in addition to its more known use in light-emitting devices.

In pursuing novel efficient lighting technologies and materials, phosphorescent cyclometallated Ir(iii) complexes have been prominent due to their wide color arrays and highly efficient electroluminescence. Their photophysical properties are strongly influenced by spin-orbit coupling exerted by the iridium core, usually resulting in intense, short-lived emission, which can be systematically tuned as a triumph of molecular engineering. This Perspective aims to present recent breakthroughs and state of the art on emissive Ir(iii) compounds, in particular a personal account on heteroleptic [Ir(N^C)2(L^X)](+) complexes, addressing the mechanistic concepts behind their luminescence. Their fascinating photophysical properties strengthen application in more-efficient light-emitting technologies, such as organic light-emitting diodes and light-emitting electrochemical cells.

In this section the governing equations of the drift-diffusion model implemented in Setfos 4.6 1 are explained. The quantities are described in the next section.

In our search for light powered molecular devices, a novel fac-[Re(CO)(phphen)(trans-stpyCN)] complex was synthesized to show switchable trans-cis configurations of the coordinated stpyCN ligand through efficient and reversible photoassisted isomerizations. Controlled photolyses of acetonitrile solutions led to spectral changes ascribed to reversible trans⇌cis photoisomerization processes. A remarkable quantum yield for the back cis-to-trans isomerization was obtained, with the same magnitude of the trans-to-cis photoprocess, and curiously, both trans- and cis-isomers are emissive at room temperature. Photochemical and photophysical characterization studies for fac-[Re(CO)(phphen)(stpyCN)] provided insights into the isomerization and emissive light-driven pathways that are resulted from the interactions between the close-lying intraligand and charge transfer states. The reversible cis-trans photoisomerization has potential to be exploited as light-powered molecular motors and geometry regulators in molecular machines.

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Vacuum deposition of perovskite solar cells can achieve efficiencies rivaling solution-based methods and allows for more complex device stacks. MoO3 has been used to enhance carrier extraction to the transparent bottom electrode in a p-i-n configuration; here, we show that by inserting an molecular interlayer with a lone pair nitrogen atom and low ionization potential, it can also be used on the top of a perovskite absorber in a n-i-p configuration. This strategy enables the first vacuum-deposited perovskite solar cells with metal oxides as charge transporting layers for both electrons and holes, leading to power conversion efficiency >19%.

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Herein, the long‐term stability of vacuum‐deposited methylammonium lead iodide (MAPbI3) perovskite solar cells (PSCs) with power conversion efficiencies (PCEs) of around 19% is evaluated. A low‐temperature atomic layer deposition (ALD) Al2O3 coating is developed and used to protect the MAPbI3 layers and the solar cells from environmental agents. The ALD encapsulation enables the MAPbI3 to be exposed to temperatures as high as 150 °C for several hours without change in color. It also improves the thermal stability of the solar cells, which maintain 80% of the initial PCEs after aging for ≈40 and 37 days at 65 and 85 °C, respectively. However, room‐temperature operation of the solar cells under 1 sun illumination leads to a loss of 20% of their initial PCE in 230 h. Due to the very thin ALD Al2O3 encapsulation, X‐ray diffraction can be performed on the MAPbI3 films and completed solar cells before and after the different stress conditions. Surprisingly, it is found that the main effect of light soaking and thermal stress is a crystal reorientation with respect to the substrate from (002) to (202) of the perovskite layer, and that this reorientation is accelerated under illumination.