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OLED technology beyond small or expensive devices requires light-emitters, luminophores, based on earth-abundant elements. Understanding and experimental verification of charge transfer in luminophores are needed for this development. An organometallic multicore Cu complex comprising Cu–C and Cu–P bonds represents an underexplored type of luminophore. To investigate the charge transfer and structural rearrangements in this material, we apply complementary pump-probe X-ray techniques: absorption, emission, and scattering including pump-probe measurements at the X-ray free-electron laser SwissFEL. We find that the excitation leads to charge movement from C- and P- coordinated Cu sites and from the phosphorus atoms to phenyl rings; the Cu core slightly rearranges with 0.05 Å increase of the shortest Cu–Cu distance. The use of a Cu cluster bonded to the ligands through C and P atoms is an efficient way to keep structural rigidity of luminophores. Obtained data can be used to verify computational methods for the development of luminophores. OLED materials based on thermally activated delayed fluorescence have promising efficiency. Here, the authors investigate an organometallic multicore Cu complex as luminophore, by pump-probe X-ray techniques at three different facilities deriving a complete picture of the charge transfer in the triplet excited state.

Optoelectronic tweezers (OET) are a promising technique for the realization of reconfigurable systems suitable to trap and manipulate microparticles. In particular, dielectrophoretic (DEP) forces produced by OET represent a valid alternative to micro-fabricated metal electrodes, as strong and spatially reconfigurable electrical fields can be induced in a photoconductive layer by means of light-driven phenomena. In this paper we report, and compare with the experimental data, the results obtained by analyzing the spatial configurations of the DEP-forces produced by a 532 nm laser beam, with Gaussian intensity distribution, impinging on a Fe-doped Lithium Niobate substrate. Furthermore, we also present a promising preliminary result for water-droplets trapping, which could open the way to the application of this technique to biological samples manipulation.

We report on the implementation of a multi-kHz single-shot referenced non-coherent two-dimensional UV spectrograph based on conventional pump-probe geometry. It has the capability to cover a broad spectral region in excitation from 270-to-380 nm and in the detection from 270-to-390 nm and 320-to-720 nm. Other setups features are: an unprecedented time resolution of 33 fs (standard deviation); signals are photometrically corrected; a single-shot noise of <1 mOD. It has the capability to operate with sample volumes as small as few μ l which is an accomplishment in studying biological or biomimetic systems. To show its performances and potentials, we report two preliminary studies on the photophysics of phenanthrenes hosted in a multichromophoric antenna system and of aromatic amino acids in a blue-copper azurin.