Search results for "F100"
showing 8 items of 8 documents
Exceptionally long-lived light-emitting electrochemical cells: multiple intra-cation π-stacking interactions in [Ir(C^N)2(N^N)][PF6] emitters
2015
A series of cyclometalated iridium(iii) complexes [Ir(C^N)2(N^N)][PF6] (N^N = 2,2′-bipyridine (1), 6-phenyl-2,2′-bipyridine (2), 4,4′-di-tert-butyl-2,2′-bipyridine (3), 4,4′-di-tert-butyl-6-phenyl-2,2′-bipyridine (4); HC^N = 2-(3-phenyl)phenylpyridine (HPhppy) or 2-(3,5-diphenyl)phenylpyridine (HPh2ppy)) are reported. They have been synthesized using solvento precursors so as to avoid the use of chlorido-dimer intermediates, chloride ion contaminant being detrimental to the performance of [Ir(C^N)2(N^N)][PF6] emitters in light-electrochemical cell (LEC) devices. Single crystal structure determinations and variable temperature solution 1H NMR spectroscopic data confirm that the pendant pheny…
Focus on the Essential: Extracting the Decisive Energy Barrier of a Complex Process
2019
Molecular processes at surfaces can be composed of a rather complex sequence of steps. The kinetics of even seemingly simple steps are demonstrated to depend on a multitude of factors, which prohibits applying a simple Arrhenius law. This complexity can make it challenging to experimentally determine the kinetic parameters of a single step. However, a molecular-level understanding of molecular processes such as structural transitions requires elucidating the atomistic details of the individual steps. Here, a strategy is presented to extract the energy barrier of a decisive step in a very complex structural transition by systematically addressing all factors that impact the transition kineti…
[Cu(bpy)(P^P)]+ containing light-emitting electrochemical cells: improving performance through simple substitution
2014
Light-emitting electrochemical cells (LECs) containing [Cu(POP)(N^N)][PF6] (POP = bis(2-diphenylphosphinophenyl)ether, N^N = 6-methyl- or 6,6′-dimethyl-2,2′-bipyridine) exhibit luminance and efficiency surpassing previous copper(i)-containing LECs.
Luminescent copper(i) complexes with bisphosphane and halogen-substituted 2,2′-bipyridine ligands
2018
Heteroleptic [Cu(P^P)(N^N)][PF6] complexes, where N^N is a halo-substituted 2,2'-bipyridine (bpy) and P^P is either bis(2-(diphenylphosphino)phenyl)ether (POP) or 4,5-bis(diphenylphosphino)-9,9- dimethylxanthene (xantphos) have been synthesized and investigated. To stabilize the tetrahedral geometry of the copper(I) complexes, the steric demands of the bpy ligands have been increased by introducing 6- or 6,6'-halo-substituents in 6,6'-dichloro-2,2'-bipyridine (6,6'-Cl2bpy), 6-bromo-2,2'- bipyridine (6-Brbpy) and 6,6'-dibromo-2,2'-bipyridine (6,6'-Br2bpy). The solid-state structures of [Cu(POP)(6,6'-Cl2bpy)][PF6], [Cu(xantphos)(6,6'-Cl2bpy)][PF6].CH2Cl2, [Cu(POP)(6-Brbpy)][PF6] and [Cu(xantp…
Highly luminescent perovskite–aluminum oxide composites
2015
In this communication we report on the preparation of CH3NH3PbBr3 perovskite/Al2O3 nanoparticle composites in a thin film configuration and demonstrate their high photoluminescence quantum yield. The composite material is solution-processed at low temperature, using stable alumina nanoparticle dispersions. There is a large influence of the alumina nanoparticle concentration on the perovskite morphology and on its photoluminescence.
Origin of the Enhanced Photoluminescence Quantum Yield in MAPbBr 3 Perovskite with Reduced Crystal Size
2018
Methylammonium lead bromide perovskite (MAPbBr3) has been widely investigated for applications in visible perovskite light-emitting diodes (LEDs). Fine-tuning of the morphology and of the crystal size, from the microscale down to the quantum confinement regime, has been used to increase the photoluminescence quantum yield (PLQY). However, the physical processes underlying the PL emission of this perovskite remain unclear. Here, we elucidate the origin of the PL emission of polycrystalline MAPbBr3 thin films by different spectroscopic techniques. We estimate the exciton binding energy, the reduced exciton effective mass, and the trap density. Moreover, we confirm the coexistence of free carr…
Perovskite solar cells prepared by flash evaporation
2015
A simple vacuum deposition method for the preparation of high quality hybrid organic-inorganic methylammonium lead iodide perovskite thin films is reported. When sandwiched in between organic charge transporting layers, such films lead to solar cells with a power conversion efficiency of 12.2%.
Efficient photovoltaic and electroluminescent perovskite devices.
2015
Planar diode structures employing hybrid organic–inorganic methylammonium lead iodide perovskites lead to multifunctional devices exhibiting both a high photovoltaic efficiency and good electroluminescence. The electroluminescence strongly improves at higher current density applied using a pulsed driving method.