Sandwich-Like Encapsulation of a Highly Luminescent Copper(I) Complex

A small molecular weight cationic copper(I) complex showing high luminescence quantum yield based on a thermally activated delayed fluorescence mechanism is immobilized between two 1 nm thin silicate layers. Partial ion exchange of the emitter into a synthetic layered silicate (fluorohectorite) yields an ordered heterostructure with two types of strictly alternating interlayers: a monolayer of the cationic emitter and a monolayer of hydrated Na+ cations. Osmotic swelling of the latter produces dispersions of double-stacks in which the emitter monolayer is encapsulated between two silicate layers. The electrostatic attraction of the emitter interlayer with the oppositely charged silicate layers exerts electrostatic pressure on the emitter. Compared to crystalline salt, rigid confinement for the encapsulated emitter provides improved thermal stability and increased emission quantum yield at ambient temperature. The suspension of delaminated, micrometer-sized double-stacks of 3.9 nm thickness allows for easy solution processing of low-cost optoelectronic devices, such as light-emitting electrochemical cells and organic light-emitting diodes

Halocuprate(I) Zigzag Chain Structures with N-Methylated DABCO Cations – Bright Metal-Centered Luminescence and Thermally Activated Color Shifts

Two compounds 1,4-dimethyl-1,4-diazoniabicyclo[2.2.2]octane catena-tetra-μ-halo-dicuprate(I) with DABCOMe2 Cu2X4 (1: X = Br, 2: X = I) were synthesized by hydrothermal reaction of copper(I) halides with the corresponding 1,4-diazoniabicyclo[2.2.2]octane (DABCO) dihydrohalides in an acetonitrile/methanol mixture. Both compounds crystallize monoclinically, 1 with a = 9.169(4) Å, b = 10.916(6) Å, c = 15.349(6) Å, β = 93.93(2)°, V = 1533(1) Å3, Z = 4, space group P21/n (no. 14) and 2 with a = 15.826(9) Å, b = 9.476(5) Å, c = 22.90(2) Å, β = 90.56(5)°, V = 3434(5) Å3, Z = 8, space group P21 (no. 4), respectively (lattice constants refined from powder diffraction data measured at 293 K). The cations in both compounds are formed by in situ N-methylation of DABCOH22+ cations by methanol in a SN2 reaction. Both compounds contain an anionic copper(I) halide chain structure consisting of trans edge-sharing CuX4 tetrahedra. The chains are strongly kinked at every 2nd junction thus forming a zigzag structure. The shortest halide-halide distances are observed between the halide ions of adjacent tetrahedra which are approaching each other due to the kinking. This structure type shows a specific luminescence behavior. Under optical excitation, the compounds exhibit yellow (1) and green (2) emission with photoluminescence quantum yields of ΦPL = 52 and 4%, respectively, at ambient temperature. According to DFT and TDDFT calculations, the emission is assigned to be a phosphorescence essentially involving a metal centered transition between the HOMO consisting mainly of copper 3d and halide p orbitals and the LUMO consisting mainly of copper 4s and 4p orbitals. The temperature dependence of the emission spectra, decay times, and quantum yields has been investigated in detail, especially for 1. From the resulting trends it can be concluded that the emission for T ≤ 100 K stems from energetically lower lying copper halide segments. Such segments represent the structural motif of the halocuprate(I) chains. With increasing temperature energetically higher lying segments are populated which also emit, but open the pathway for thermally activated energy transfer to quenching defects

Status of the BELLE II Pixel Detector

The Belle II experiment at the super KEK B-factory (SuperKEKB) in Tsukuba, Japan, has been collecting $e^+e^−$ collision data since March 2019. Operating at a record-breaking luminosity of up to $4.7×10^{34} cm^{−2}s^{−1}$, data corresponding to $424 fb^{−1}$ has since been recorded. The Belle II VerteX Detector (VXD) is central to the Belle II detector and its physics program and plays a crucial role in reconstructing precise primary and decay vertices. It consists of the outer 4-layer Silicon Vertex Detector (SVD) using double sided silicon strips and the inner two-layer PiXel Detector (PXD) based on the Depleted P-channel Field Effect Transistor (DePFET) technology. The PXD DePFET structure combines signal generation and amplification within pixels with a minimum pitch of $(50×55) μm^2$. A high gain and a high signal-to-noise ratio allow thinning the pixels to $75 μm$ while retaining a high pixel hit efficiency of about $99$. As a consequence, also the material budget of the full detector is kept low at $≈0.21$$\frac{X}{X_0}$ per layer in the acceptance region. This also includes contributions from the control, Analog-to-Digital Converter (ADC), and data processing Application Specific Integrated Circuits (ASICs) as well as from cooling and support structures. This article will present the experience gained from four years of operating PXD; the first full scale detector employing the DePFET technology in High Energy Physics. Overall, the PXD has met the expectations. Operating in the intense SuperKEKB environment poses many challenges that will also be discussed. The current PXD system remains incomplete with only 20 out of 40 modules having been installed. A full replacement has been constructed and is currently in its final testing stage before it will be installed into Belle II during the ongoing long shutdown that will last throughout 2023

Photophysical characterizations of OLED relevant Cu(I) complexes exhibiting thermally activated delayed fluorescence (TADF)

In this thesis, different classes of OLED relevant Cu(I) complexes as well as one Ag(I) complex were investigated especially with regard to their photophysical properties. Hereby, the main focus was to establish a relationship between the molecular structure of the compounds and their emission properties. To achieve this, for each compound class different, systematically varied substances were studied. Hereby, dinuclear halide-bridged Cu(I) and Ag(I) complexes with aminophosphine and diphosphine ligands as well as mononuclear Cu(I) complexes with three or four coordinations were in the focus of the investigations. To obtain insight into the electronic structures, the emission behavior of the substances was studied in a wide temperature range between T = 1.3 K and 300 K. In addition, for some compounds also the influence of the surrounding matrix environment on the emission behavior was investigated. Furthermore, density functional theory (DFT) and time-dependent density functional theory (TDDFT) calculations have been performed to gain a more profound insight into the electronic states that determine the emission behavior of the compounds. The performed measurements allowed to develop a detailed understanding for the photophysical properties, such as emission decay time, emission color, and emission quantum yield and how these properties can be changed by defined chemical modifications. In addition, for most of the studied substances the occurrence of a thermally activated delayed fluorescence (TADF) could be proven. Furthermore, the mechanisms that control the occurrence of a TADF could be elucidated. Through this, valuable insights could be gained for future developments of novel, efficient emitters for OLED applications based on Cu(I) and Ag(I) complexes

A new class of deep-blue emitting Cu(I) compounds – effects of counter ions on the emission behavior

Three deep blue emitting Cu(I) compounds, [Cu(PPh3)tpym]PF6, [Cu(PPh3)tpym]BF4, and [Cu(PPh3)tpym]BPh4 (tpym = tris(2-pyridyl)methane, PPh3 = triphenylphosphine) featuring the tripodally coordinating tpym and the monodentate PPh3 ligands were studied with regard to their structural and photophysical properties. The compounds only differ in their respective counter ions which have a strong impact on the emission properties of the powder samples. For example, the emission quantum yield can be significantly increased for the neat material from less than 10% to more than 40% by exchanging BPh4− with PF6−. These effects can be linked to different molecular packings which depend on the counter ion. In agreement with these results, it was found that the emission properties also strongly depend on the surrounding matrix environment which was elucidated by investigating photophysical properties of the compounds as powders, doped into a polymer matrix, and dissolved in a fluid solution, respectively. The observed differences in the emission behavior can be explained by different and pronounced distortions that occur in the excited state. These distortions are also displayed by density functional theory (DFT) calculations

A new class of luminescent Cu(I) complexes with tripodal ligands – TADF emitters for the yellow to red color range

A new class of emissive and neutral Cu(I) compounds with tripodal ligands is presented. The complexes were characterized chemically, computationally, and photophysically. Under ambient conditions, the powders of the compounds exhibit yellow to red emission with quantum yields ranging from about 5% to 35%. The emission represents a thermally activated delayed fluorescence (TADF) combined with a short-lived phosphorescence which represents a rare situation and is a consequence of high spin–orbit coupling (SOC). In the series of the investigated compounds the non-radiative rates increase with decreasing emission energy according to the energy gap law while the radiative rate is almost constant. Furthermore, a well-fit linear dependence between the experimental emission energies and the transition energies calculated by DFT and TD-DFT methods could be established, thus supporting the applicability of these computational methods also to Cu(I) complexes

Long-term Outcome of the Retrourethral Transobturator Male Sling After Transurethral Resection of the Prostate

Purpose To evaluate long-term outcomes of AdVance and AdVanceXP male slings in patients with persistent stress urinary incontinence (SUI) after transurethral resection of the prostate (TURP). Methods A total of 18 consecutive patients received AdVance (n=14) or AdVanceXP (n=4) male sling implantation between 2007 and 2013. Continence was determined by pad use, 24-hour pad testing and validated questionnaires (International Consultation on Incontinence Questionnaire Short Form, ICIQ-SF). Quality of life was evaluated by International Quality of Life (IQoL) score. Patient satisfaction was measured with patient’s global impression of improvement score. Cure was defined as 0–5 g in the 24-hour pad test. Statistical analysis included Fisher exact and Wilcoxon test (P<0.05). Results Follow-up was available for 15 patients who underwent further analysis. After a median follow-up of 70 months (range, 18–83 months), mean daily pad usage was 1.8±2.1 pads (P=0.015 vs. baseline level). Mean IQoL score was 66.4±31.6 (P=0.050 vs. baseline level), and mean ICIQ-SF score was 9.5±6.6 (P=0.077 vs. baseline level). Based on 24-hour pad testing, mean daily urine loss was 31.2±64.5 g (median, 0 g; range, 0–209 g). Cure rate was 46.7%, and cure-and-improved rate was 60.0%. Assessing predictive features for success, better results were found in patients who needed up to 4 pads preoperatively (P=0.041) as well as for patients ≤71 years at the time of implantation (P=0.041). Conclusions The findings indicate that AdVance and AdVanceXP implantation can be performed effectively and safely in men suffering from SUI after TURP. However, long-term success rates seem to be lower compared to SUI after radical prostatectomy and patients should be counseled accordingly

Phosphorescence versus Thermally Activated Delayed Fluorescence. Controlling Singlet–Triplet Splitting in Brightly Emitting and Sublimable Cu(I) Compounds

Photophysical properties of two highly emissive three-coordinate Cu­(I) complexes, (IPr)­Cu­(py₂-BMe₂) (<b>1</b>) and (Bzl-3,5Me)­Cu­(py₂-BMe₂) (<b>2</b>), with two different N-heterocyclic (NHC) ligands were investigated in detail (IPr = 1,3-bis­(2,6-diisopropylphenyl)­imidazol-2-ylidene; Bzl-3,5Me = 1,3-bis­(3,5-dimethylphenyl)-1<i>H</i>-benzo­[<i>d</i>]­imidazol-2-ylidene; py₂-BMe₂ = di­(2-pyridyl)­dimethylborate). The compounds exhibit remarkably high emission quantum yields of more than 70% in the powder phase. Despite similar chemical structures of both complexes, only compound <b>1</b> exhibits thermally activated delayed blue fluorescence (TADF), whereas compound <b>2</b> shows a pure, yellow phosphorescence. This behavior is related to the torsion angles between the two ligands. Changing this angle has a huge impact on the energy splitting between the first excited singlet state S₁ and triplet state T₁ and therefore on the TADF properties. In addition, it was found that, in both compounds, spin–orbit coupling (SOC) is particularly effective compared to other Cu­(I) complexes. This is reflected in short emission decay times of the triplet states of only 34 μs (<b>1</b>) and 21 μs (<b>2</b>), respectively, as well as in the zero-field splittings of the triplet states amounting to 4 cm^–1 (0.5 meV) for <b>1</b> and 5 cm^–1 (0.6 meV) for <b>2</b>. Accordingly, at ambient temperature, compound <b>1</b> exhibits <i>two</i> radiative decay paths which are thermally equilibrated: one via the S₁ state as TADF path (62%) and one via the T₁ state as phosphorescence path (38%). Thus, if this material is applied in an organic light-emitting diode, the generated excitons are harvested mainly in the singlet state, but to a significant portion also in the triplet state. This novel mechanism based on two separate radiative decay paths reduces the overall emission decay time distinctly