Controlling the emission efficiency of blue-green iridium (iii) phosphorescent emitters and applications in solution-processed organic light-emitting diodes

We show that the emission efficiency of blue-green phosphorescent emitters can be controlled through coupling of the excited state to vibrational modes. We controlled this vibrational coupling through choice of different ligands and as a result, complexes with CF3-groups on the ancillary ligand were essentially non-emissive (ΦPL 50%). Emission of the complexes can be drastically improved (30 times higher ΦPL compared to degassed solution for the CF3-containing complexes) by blending them with an inert solid host such as PMMA, which mitigates metal-ligand vibrations. Solution-processed organic light-emitting diodes made from these materials showed efficiency as high as 6.3%

Borylation–Reduction–Borylation for the Formation of 1,4-Azaborines

This project has received funding from the Leverhulme Trust (grant Number RPG-2022-032) and the European Research Council (ERC) under the European Union’s Horizon 2020 research and innovation program (Grant Agreement No. 769599). M.J.I. and E.Z.-C. also thank the EPSRC Programme Grant “Boron: Beyond the Reagent” (EP/W007517/1) for support.Given the current interest in materials containing 1,4-azaborine units, the development of new routes to these structures is important. Carbonyl directed electrophilic borylation using BBr3 is a facile method for the ortho-borylation of N,N-diaryl-amide derivatives. Subsequent addition of Et3SiH results in carbonyl reduction and then formation of 1,4-azaborines that can be protected in situ using a Grignard reagent. Overall, borylation–reduction–borylation is a one-pot methodology to access 1,4-azaborines from simple precursors.Publisher PDFPeer reviewe

Conformations of large macrocycles and ring-in-ring complexes

This work was supported by the Swiss National Science Foundation.A kinetically directed, stepwise approach towards molecular Borromean links enabled the isolation and structural characterization of synthetic intermediates along the way. Here we report the synthesis and crystal structures of three flexible macrocyclic intermediates and a new ring-in-ring complex, anchored together through ruthenium(ii) centers, which contains open terpyridine caps in the inner Ring II. Terpyridines circumvent the conformational cis/trans limitations of bipyridines and the new ring-in-ring complex forms tetrametallic complexes with Zn(ii), Pt(ii) and Ru(iii) metal ions. Analysis of the four macrocyclic structures provides a good foundation for the conformational flexibility in these complexes and demonstrates the robust applicability of the terpyridine design elements towards the engineered synthesis of ring-in-ring topologies.Publisher PDFPeer reviewe

Towards a better use of psychoanalytic concepts: a model illustrated using the concept of enactment

It is well known that there is a lack of consensus about how to decide between competing and sometimes mutually contradictory theories, and how to integrate divergent concepts and theories. In view of this situation the IPA Project Committee on Conceptual Integration developed a method that allows comparison between different versions of concepts, their underlying theories and basic assumptions. Only when placed in a frame of reference can similarities and differences be seen in a methodically comprehensible and reproducible way. We used "enactment" to study the problems of comparing concepts systematically. Almost all psychoanalytic schools have developed a conceptualization of it. We made a sort of provisional canon of relevant papers we have chosen from the different schools. The five steps of our method for analyzing the concept of enactment will be presented. The first step is the history of the concept; the second the phenomenology; the third a methodological analysis of the construction of the concept. In order to compare different conceptualizations we must know the main dimensions of the meaning space of the concept, this is the fourth step. Finally, in step five we discuss if and to what extent an integration of the different versions of enactment is possible

Controlling the emission efficiency of blue-green iridium(III) phosphorescent emitters and applications in solution-processed organic light-emitting diodes

We are grateful to the European Research Council (grant 321305), EPSRC (grants EP/J01771X/1, EP/L017008/1 and EP/M02105X/1) for financial support. IDWS acknowledges a Royal Society Wolfson Research Merit Award. GSH thanks the Natural Sciences and Engineering Research Council (NSERC) of Canada for funding.We show that the emission efficiency of blue-green phosphorescent emitters can be controlled through coupling of the excited state to vibrational modes. We controlled this vibrational coupling through choice of different ligands and as a result, complexes with CF3-groups on the ancillary ligand were essentially non-emissive (ΦPL 50%). Emission of the complexes can be drastically improved (30 times higher ΦPL compared to degassed solution for the CF3-containing complexes) by blending them with an inert solid host such as PMMA, which mitigates metal-ligand vibrations. Solution-processed organic light-emitting diodes made from these materials showed efficiency as high as 6.3%.PostprintPeer reviewe

Identification of the key parameters for horizontal transition dipole orientation in fluorescent and TADF organic light-emitting diodes

This research was financially supported by the Volkswagen Foundation (No. 93404), the European Commission under EU Horizon 2020 Grant Agreement No. 812872 (TADFlife), the European Research Council under the European Union's Horizon 2020 Framework Programme (FP/2014-2020)/ERC grant agreement no. 640012 (ABLASE), and The Leverhulme Trust (RPG-2016047). M.C.G. acknowledges support from the Alexander von Humboldt Stiftung through the Humboldt-Professorship. All computations were performed using resources kindly provided by the University of Mons (UMONS), supported by the Belgian National Fund for Scientific Research (FRS-FNRS). Computational resources were provided by the Consortium des Équipements de Calcul Intensif (CÉCI) funded by F.R.S.-FNRS under Grant 2.5020.11. Y.O. acknowledges funding from the FRS-FNRS under the grant F.4534.21 (MIS-IMAGINE).In organic light-emitting diodes (OLEDs), horizontal orientation of the emissive transition dipole moment (TDM) can improve light outcoupling efficiency by up to 50% relative to random orientation. Therefore, there have been extensive efforts to identify drivers of horizontal orientation. The aspect ratio of the emitter molecule and the glass-transition temperature (Tg) of the films are currently regarded as particularly important. However, there remains a paucity of systematic studies that establish the extent to which these and other parameters control orientation in the wide range of emitter systems relevant for state-of-the-art OLEDs. Here, recent work on molecular orientation of fluorescent and thermally activated delayed fluorescent emitters in vacuum-processed OLEDs is reviewed. Additionally, to identify parameters linked to TDM orientation, a meta-analysis of 203 published emitter systems is conducted and combined with density-functional theory calculations. Molecular weight (MW) and linearity are identified as key parameters in neat systems. In host–guest systems with low-MW emitters, orientation is mostly influenced by the host Tg, whereas the length and MW of the emitter become more relevant for systems involving higher-MW emitters. To close, a perspective of where the field must advance to establish a comprehensive model of molecular orientation is given.Publisher PDFPeer reviewe

Blue emissive cobalt(III) complexes and their use in the photocatalytic trifluoromethylation of polycyclic aromatic hydrocarbons

A.K.P and G.S.H thank Natural Sciences and Engineering Research Council of Canada. A.K.P thanks the Leverhulme Trust Early Career Fellowship (ECF-2017-326) and the University of St Andrews. The authors thank the Prof. & Mrs Purdie Bequests Scholarship and AstraZeneca support for C.L. EZ-C thanks the Engineering and Physical Sciences Research Council (EP/M02105X/1) and the University of St Andrews.The first examples of room temperature (r.t.) luminescent Co(III) complexes ( 1 and 2 ) are presented that exhibit intense ligand‐to‐metal and ligand‐to‐ligand charge transfer absorption in the low energy UV region (λabs ~ 360‐400 nm) and low‐negative quasi‐reversible reduction events (E1/2(red) = −0.58 V and −0.39 V vs. SCE for 1 and 2 , respectively). The blue emission of 1 and 2 at r.t. is due to the large bite angles and strong σ‐donation of the ligands, the combined effect of which helps to separate the emissive 3LMCT (triplet ligand‐to‐metal charge transfer) and the non‐emissive 3MC (triplet metal‐centered) states. 1 and 2 were found to be powerful photo‐oxidants (ECo(III)*/Co(II) = 2.26 V and 2.75 V vs. SCE of 1 and 2 , respectively) and were used as inexpensive photoredox catalysts for the regioselective mono(trifluoromethylation) of polycyclic aromatic hydrocarbons (PAHs) in good yields (~ 40‐58%).PostprintPeer reviewe

Effect of a twin-emitter design strategy on a previously reported thermally activated delayed fluorescence organic light-emitting diode

In this work we showcase the emitter DICzTRZ in which we employed a twin-emitter design of our previously reported material, ICzTRZ. This new system presented a red-shifted emission at 488 nm compared to that of ICzTRZ at 475 nm and showed a comparable photoluminescence quantum yield of 57.1% in a 20 wt % CzSi film versus 63.3% for ICzTRZ. The emitter was then incorporated within a solution-processed organic light-emitting diode that showed a maximum external quantum efficiency of 8.4%, with Commission Internationale de l’Éclairage coordinate of (0.22, 0.47), at 1 mA cm$^{-2}

In the dedicated pursuit of dedicated capital: restoring an indigenous investment ethic to British capitalism

Tony Blair’s landslide electoral victory on May 1 (New Labour Day?) presents the party in power with a rare, perhaps even unprecedented, opportunity to revitalise and modernise Britain’s ailing and antiquated manufacturing economy.* If it is to do so, it must remain true to its long-standing (indeed, historic) commitment to restore an indigenous investment ethic to British capitalism. In this paper we argue that this in turn requires that the party reject the very neo-liberal orthodoxies which it offered to the electorate as evidence of its competence, moderation and ‘modernisation’, which is has internalised, and which it apparently now views as circumscribing the parameters of the politically and economically possible