A novel series of cyclometalated platinum(II) complexes bearing acyclic diaminocarbene (ADC) ancillary ligands were designed and prepared. Their photophysical properties were systematically studied through experimental and theoretical investigations. All complexes exhibit green phosphorescence with a quantum efficiency of up to 45% in 2 wt% doped PMMA film at room temperature. The complexes are used as light-emitting dopants for organic light-emitting diode (OLED) fabrication. The devices displayed a green emission with a maximum current efficiency of 2.9 cd A⁻¹ and a luminance of 2700 cd m⁻². These results show that these cyclometalated platinum(II) complexes can be used as efficient green emitting components of OLED devices.

Silicon nanophotonics has become a versatile platform for optics and optoelectronics. For example, strong light localization at the nanoscale and lack of parasitic losses in infrared and visible spectral ranges make resonant silicon nanoparticles a prospect for improvement in such rapidly developing fields as photovoltaics. Here, we employed optically resonant silicon nanoparticles produced by laser ablation for boosting the power conversion efficiency of organic solar cells. Namely, we created colloidal solutions of spherical nanoparticles with a range of diameters (80–240 nm) in different solvents. We tested how the nanoparticles’ position in the device, their concentration, silicon doping, and method of deposition affected the final device efficiency. The best conditions optimization resulted in an efficiency improvement from 6% up to 7.5%, which correlated with numerical simulations of nanoparticles’ optical properties. The developed low-cost approach paves the way toward highly efficient and stable solution-processable solar cells.

An approach to increase the efficiency of europium-based OLEDs was proposed through the formation of a mixed-ligand complex. The design of a series of europium complexes, together with an optimization of the solution deposition, including the host selection, as well as the variation of the solvent and deposition parameters, resulted in a noticeable increase in OLED luminance. As a result, the maximum luminance of the Eu-based OLED reached up to 700 cd/m², which is one of the highest values for an Eu-based solution-processed OLED. Finally, its stability was investigated.

Quasi-two-dimensional (quasi-2D) perovskites show great potential in light-emitting diodes. The use of additives plays a key role in the passivation of defects and the suppression of low-dimensional phases. However, the effects of additives vary greatly in different perovskite formulations/films with different light-emitting bands. In this paper, the universal utility of additives was achieved through sodium hexafluorophosphate (NaPF₆). Benefitting from the neutral environment of the additives and the hydrogen bonds formed by PF₆ ⁻/PEA⁺ (F⋯H–N), the low-dimensional phases are effectively reduced, and the distribution of the medium/high-dimensional phases is more balanced. Meanwhile, the PF₆ ⁻ anionic group can passivate the uncoordinated Pb²⁺, and reduce the defect density of the film. Finally, a maximum EQE of 16.8% was achieved in quasi-2D PEA₂Cs_n−1Pb_nBr_3n+1 green PeLEDs (514 nm), which was significantly higher than that of the pristine device (a maximum EQE of 10%). Correspondingly, the maximum EQE of sky blue PeLEDs (490 nm) based on the mixed halogen [(PEA)_0.75(GA)_0.25]₂CsPb₂X₇ (X = Br and Cl) component can be increased from 5.6% to 9.6%. The maximum EQE of pure blue PeLEDs (474 nm) can be increased from 3% to 4%. This class of neutral additives provides a solution for high-performance quasi-2D perovskite electroluminescence.

As alternatives to conventional perovskite light-emitting diodes, perovskite light-emitting electrochemical cells (PeLECs) are in great demand in modern science and technology due to their simplified structure and attainable higher luminance. Here, for the first time, we present the implementation and characterization of red CsPbIBr₂-based PeLECs/LEDs. To improve perovskite material phase stability, we applied the following strategies for mitigating the mixed anion lead halide perovskite phase segregation: Pb²⁺ partial substitution by Mn²⁺, boundary passivation by poly(ethylene oxide) with polyvinylidene fluoride, and two-step thermal treatment with vacuuming and annealing. The complex measurements of photoluminescence, optical density, energy-dispersive X-ray spectroscopy, and X-ray diffraction confirm the minor phase segregation in the optimized perovskite layers. The performed ab-initio calculations predicted the band gaps of perovskite materials with a mixed anion composition, corresponding well to the results of optical measurements. Finally, current and electroluminescence time tracking proved the formation of a dynamic p–i–n structure in the studied PeLEC devices. The developed PeLECs/LEDs exhibited relatively high, for red PeLECs, electroluminescence up to 96 cd m⁻² with a peak position at 667–672 nm.