From the reaction of LiTePh and dppm(AuCl)2, a water and air stable gold-tellurolate cluster featuring a novel core structure can be obtained in good yield. The cluster with the formula [Au8(TePh)4dppm2(Ph2PCHPPh2)2]Cl21 exhibits two Au4 units with Au-Au distances in the range from 295.4 pm to 335.1 pm. Crystals of 1 show red luminescence with a high Stokes shift and an excellent quantum yield (Φ = 0.28), demonstrating that 1 is a promising red phosphor for pc-LED applications.

The reaction of dppm(AuCl) 2 with LiTePh affords the water and air stable gold-tellurolate cluster [Au 8 (TePh) 4 dppm 2 (Ph 2 PCHPPh 2 ) 2 ]Cl 2 , which shows a bright red luminescence with excellent quantum yield.

The application of rare-earth complexes in electrically driven light sources poses a series of challenges that require specific optimization of the molecular photophysical properties. Here, we present a report on films of three different Eu3+ complexes characterized in terms of emission spectra and fluorescence decay. We compare molecular complexes in powder form and sublimed films, in films on glass and on a metal surface, and in films of thicknesses down to less than 3 nm (< 3 ML), approaching electrical coupling. Our photoluminescence experiments supported by scanning tunneling microscopy of sub-monolayers indicate that Eu3+(trensal) complexes are less affected by sublimation and more stable on the metal surface than typical beta diketonate complexes, making them promising candidates for electroluminescence devices.

The reaction of dppb(AuCl)2 and InCl gives the [Au4(dppb)3]2+ cluster where the four gold atoms are arranged in a deltoid. This contrasts all known [Au4]2+ clusters which exclusively form tetrahedral structures. Single crystals of the title compound luminesce with a high quantum yield in the near infrared at room temperature. The excitation wavelength dictates the emission wavelength which ranges from 680 to 918 nm at 77 K. Comprehensive studies of the excitation-dependent emission and luminescence lifetimes in both polycrystalline and single-crystalline samples provide a unique and detailed optical profile of the cluster, uncovering distinct photophysical behavior central to its emissive properties.

New phenanthroline-based tris(biaryl) europium(III) and ytterbium(III) cryptates with great luminescence efficiencies in solution are reported. 1,10-Phenantroline, in combination with 2,2'-bipyridine-N,N'-dioxide, delivers cryptates with high rigidity, efficient lanthanoid(III) sensitization (ηsens) and small radiative lifetimes τrad for Eu and Yb. The powerful synergy of both bidentate chelating units results in excellent absolute quantum yields of up to 20% for the europium complexes in aqueous solution, which indicates an impressive improvement compared to other well-known tris(bipyridyl)-based Eu(III) cryptates.

Since its discovery, pyrroloquinoline quinone (PQQ) has been under constant investigation regarding its efficiency in biomimetic complexes for alcohol dehydrogenation. The discovery of lanthanide (Ln) dependent methanol dehydrogenases has led to the use of lanthanide complexes bearing PQQ derivatives to oxidize alcohols. However, the mechanism of these oxidations is still a subject of debate. Herein, La3+ and Lu3+ complexes of PQQ dimethyl ester (PQQDME), that are able to stoichiometrically oxidize an alcohol substrate, are reported. In the presence of air, some catalytic turnover is observed, but less than with other, more heavily modified PQQ biomimetics known in the literature. To investigate the reason for this low turnover, the reduced counterpart, PQQDMEH2, is synthesized. It is shown that in the presence of atmospheric oxygen, the complexes of the reduced form undergo oxidation and can then also convert alcohol to aldehyde. Additionally, the involvement of radicals in the alcohol oxidation reaction and the origin and nature of these radicals is investigated.

This study comprehensively investigates the excited-state dynamics of two tungsten iodide prototype clusters, [(W6I8)I6]2- and [(W6I8)(TFA)6]2- (TFA = trifluoroacetate), utilizing a combination of ultrafast transient absorption spectroscopy from 200 fs up to 400 μs and temperature-dependent emission spectroscopy from 4 to 340 K. Both clusters exhibit rapid intersystem crossing occurring within 6 ps, populating triplet states that subsequently deactivate through emission or dynamical bimolecular quenching involving molecular oxygen. The temperature-dependent emission behavior aligns well with a group-theoretical spin-sublevel model, indicating three distinct emissive sublevels. However, contrary to previous findings in molybdenum-based clusters, no additional splitting of the lowest triplet states was observed experimentally. Time-dependent density functional theory calculations highlight substantial excited-state geometrical distortions, suggesting limitations in sole group-theoretical descriptions. Instead, we propose a relativistic model with three thermally accessible excited-state geometries, each presenting three triplet sublevels.

A new, linear octadentate chelator, "en-pypa," based on 2,2'-bipyridine-6-carboxylic acid, has been developed. This ligand can bind trivalent lanthanoids (e.g., Sm, Eu, Tb, Dy, Tm, Yb, and Lu) very rapidly and yields well-defined complexes that exhibit relatively strong luminescence in aqueous solution. This study reports the synthesis, as well as the structural and photophysical characterization. In addition, nonradiative deactivation of near-infrared luminescence by the ligand N-H oscillators is addressed by comparison of the luminescence from the Yb complexes of en-pypa and its methylated analogue.

Micro- and nanoscale fabrication, which enables precise construction of intricate three-dimensional structures, is of foundational importance for advancing innovation in plasmonics, nanophotonics, and biomedical applications. However, scaling fabrication to industrially relevant levels remains a significant challenge. We demonstrate that triplet-triplet annihilation upconversion (TTA-UC) offers a unique opportunity to increase fabrication speeds and scalability of micro- and nanoscale 3D structures. Due to its nonlinearity and low power requirements, TTA-UC enables localized polymerization with nanoscale resolutions while simultaneously printing millions of voxels per second through optical parallelization using off-the-shelf light-emitting diodes and digital micromirror devices. Our system design and component integration empower fabrication with a minimum lateral feature size down to 230 nm and speeds up to 112 million voxels per second at a power of 7.0 nW per voxel. This combination of high resolution and fast print speed demonstrates that TTA-UC is a significant advancement in nanofabrication technique, evidenced by the fabrication of hydrophobic nanostructures on a square-centimeter scale, paving the way for industrial nanomanufacturing.

Lanthanoid-antenna complexes are promising building blocks for quantum technologies, yet their potential in the condensed phase is often obscured by phonon-induced decoherence. This article reports the first one-color helium-tagging spectroscopic measurements of isolated [Ho(enpypa)]+ and [Yb(enpypa)]+ complexes (enpypa = ethylenediamine-pyridine-picolinic acid) at cryogenic temperatures, directly resolving their elusive 4f-4f excitations in the gas phase. For Ho3+, at least eight Stark-split multiplets are identified across the visible spectrum, while the Yb3+ complex exhibits a sharp 2F7/2 → 2F5/2 near-infrared manifold together with a hot band consistent with thermal equilibrium at 4 K. The UV-absorbing ligand shows depletion cross sections over two orders of magnitude larger than the lanthanoid-centered transitions, highlighting the sensitivity and dynamic range of our next-generation apparatus. These results establish cryogenic ion trap spectroscopy as a powerful tool for probing lanthanoid photophysics and pave the way for multicolor spectroscopic investigations of lanthanoid systems tailored for quantum information science.

Colloidal 2D PbX (X = S, Se, Te) nanocrystals are innovative materials pushing the boundaries of quantum confinement by combining crystal thicknesses down to a monolayer with additional confinement in the lateral dimension. These flat PbSe quantum dots (fQDs) exhibit telecommunication band photoluminescence (1.43-0.83 eV), which is highly interesting for fiber optic information processing. With scanning tunneling microscopy/spectroscopy (STM/STS), we probe single-layer-defined fQD populations down to one monolayer, showing an in-gap state free QD-like density of states in excellent agreement with theoretical tight-binding (TB) calculations. Cryogenic ensemble spectra match STS/STM and TB calculations and exhibit the contribution of mono-, bi-, and trilayers to the photoluminescence. Comparing the electronic band gaps with the optical ones, we derive exciton binding energies as high as 600 meV for PbSe monolayers. Our results allow for a target-oriented synthesis of a new class of QDs with record binding energies and precisely tailored optical properties at technologically relevant wavelengths.

Understanding the electronic structure of polycyclic aromatic compounds is of fundamental importance for their potential applications. The optoelectronic properties of shorter acenes such as tetracene and pentacene have been extensively studied with regard to excitation, emission, and nonlinear effects such as singlet fission. The longer homologues present a unique challenge due to their low stability both in the solid state and in solution. In this work, we synthesized persistent 6,8,15,17-tetrakis((triisopropylsilyl)ethynyl)heptacene and investigated its photophysical properties as well as those of the parent heptacene. Our steady-state electronic absorption and emission experiments combined with transient absorption spectroscopy show that the Franck-Condon electric-dipole-forbidden ("dark") transition to the 21Ag singlet state is the lowest-energy excited state of heptacene. This contrasts with the optical properties of the well-known shorter acenes. Transient absorption data further suggest singlet fission or intersystem crossing as potential pathways to rapid population of the triplet state facilitated by the dark singlet state.

Two-dimensional (2D) metal-halide perovskites have promising characteristics for optoelectronic applications. By incorporating Mn2+ ions into the perovskite structure, improved photoluminescence quantum yield can be achieved. This has been attributed to the formation of defect states that act as efficient recombination centers. Here, we make use of transient photoluminescence microscopy to characterize important material parameters of Mn2+-doped 2D perovskites with different doping levels. From these measurements, we visualize the importance of exciton transport as an intermediate step in the excitation of Mn2+. We model the spatiotemporal dynamics of the excited states to extract the diffusion constant and the transfer rate of the excitations to the Mn dopant sites. Interestingly, from these models, we find that the average distance an exciton needs to travel before transferring to a Mn site is significantly larger than expected from the Mn concentration obtained from elemental analysis. These insights are critical from a device design perspective.

Near-infrared emitting colloidal two-dimensional (2D) PbX (X = S, Se) nanoplatelets (NPLs) have emerged as interesting materials with strong size quantization in the thickness dimension. They act as model systems for efficient charge carrier multiplication and hold potential as intriguing candidates for fiber-based photonic quantum applications. However, synthetic access to the third family member, 2D PbTe, remains elusive due to challenging precursor chemistry. Here, we report a direct synthesis for 2D PbTe NPLs with tunable photoluminescence [PL, 910-1460 nm (1.36-0.85 eV), PL quantum yields 1-15%], based on aminophosphine precursor chemistry. Ex situ transamination of tris(dimethylamino)phosphine telluride with octylamine is confirmed by P-31 nuclear magnetic resonance and yields a reactive tellurium precursor for the formation of 2D PbTe NPLs at temperatures as low as 0 degrees C. The PL position of the PbTe NPLs is tunable by controlling the Pb/Te ratio in the reaction. Grazing-incidence wide-angle X-ray scattering confirms the 2D geometry of the NPLs and the formation of superlattices. The importance of a postsynthetic passivation of PbTe NPLs by PbI2 to ensure colloidal stability of the otherwise oxygen-sensitive samples is supported by X-ray photoelectron spectroscopy. Our results expand and complete the row of lead chalcogenide-based 2D NPLs, opening up new ways for further pushing the optical properties of 2D NPLs into the infrared and toward technologically relevant wavelengths.

Using light to control matter has captured the imagination of scientists for generations, as there is an abundance of photons at our disposal. Yet delivering photons beyond the surface to many photoresponsive systems has proven challenging, particularly at scale, due to light attenuation via absorption and scattering losses. Triplet-triplet annihilation upconversion (TTA-UC), a process which allows for low energy photons to be converted to high energy photons, is poised to overcome these challenges by allowing for precise spatial generation of high energy photons due to its nonlinear nature. With a wide range of sensitizer and annihilator motifs available for TTA-UC, many researchers seek to integrate these materials in solution or solid-state applications. In this Review, we discuss nanoengineering deployment strategies and highlight their uses in recent state-of-the-art examples of TTA-UC integrated in both solution and solid-state applications. Considering both implementation tactics and application-specific requirements, we identify critical needs to push TTA-UC-based applications from an academic curiosity to a scalable technology.

Correction for 'Distinct photodynamics of kappa-N and kappa-C pseudoisomeric iron(II) complexes' by Philipp Dierks et al., Chem. Commun., 2021, 57, 6640-6643, https://doi.org/10.1039/D1CC01716K.

Correction for 'Distinct photodynamics of kappa-N and kappa-C pseudoisomeric iron(II) complexes' by Philipp Dierks et al., Chem. Commun., 2021, 57, 6640-6643, https://doi.org/10.1039/D1CC01716K.

Correction for 'Distinct photodynamics of κ-N and κ-C pseudoisomeric iron(II) complexes' by Philipp Dierks et al., Chem. Commun., 2021, 57, 6640-6643, https://doi.org/10.1039/D1CC01716K.

Transient Photoluminescence Microscopy (TPLM) allows for the direct visualization of carrier transport in semiconductor materials with sub nanosecond and few nanometer resolution. The technique is based on measuring changes in the spatial distribution of a diffraction limited population of carriers using spatiotemporal detection of the radiative decay of the carriers. The spatial resolution of TPLM is therefore primarily determined by the signal-to-noise-ratio (SNR). Here we present a method using cylindrical lenses to boost the signal acquisition in TPLM experiments. The resulting asymmetric magnification of the photoluminescence emission of the diffraction limited spot can increase the collection efficiency by more than a factor of 10, significantly reducing acquisition times and further boosting spatial resolution.