We demonstrate an original organic light-emitting diode (OLED) having a neat liquid host of 9-(2-ethylhexyl)carbazole (EHCz) doped with a guest emitter of 5,6,11,12-tetraphenylnapthacene (rubrene). The device structure is composed of indium tin-oxide (ITO)/poly(3,4-ethylenedioxythiophene):poly(styrenesulphonate)/EHCz:rubrene/${\text{Cs}}_2{\text{CO}}_3$ /ITO. We demonstrate that the liquid organic semiconducting layer surely transports charge carriers, leading to electroluminescence from rubrene with the highest external quantum efficiency of ${\eta }_{\text{ext}}=0.03\%$ at a current density of $0.26\text{mA}/{\text{cm}}^2$ . Our demonstration of the liquid-OLEDs will open another possibility of organic semiconductors and light-emitting applications.

A series of Ba₃Lu(PO₄)₃:Sm³⁺ phosphors were prepared by traditional high temperature solid-state reaction methods. The site-preferred occupancy of Sm³⁺ in Ba₃Lu(PO₄)₃ and the luminescence properties of Ba₃Lu(PO₄)₃:Sm³⁺ were studied combined with X-ray diffraction, photoluminescence excitation (PLE) spectra, and emission (PL) spectra as well as temperature-dependent PL and decay curves. The PL intensity is improved with increasing Sm³⁺ content and the optimal dopant content is 0.05. The temperature-dependent PL spectra indicate that the emission intensity decreases with the temperature because of the enhancement of the non-radiative transition. The results indicate that these reddish-orange emitting phosphors could be for potential applications in w-LEDs.

Dopants in luminescent metal halides provide an alternative way for photoluminescence tuning towards versatile optical applications. Here we report a trivalent antimony (Sb³⁺)-doped single crystalline 0D metal halide with the composition of (C₉NH₂₀)₉[Pb₃Cl₁₁](ZnCl₄)₂:Sb³⁺. This compound possessed the coexistence of two emission centers including intrinsic and extrinsic self-trapped excitons (STEs), which are ascribed to [Pb₃Cl₁₁]⁵⁻ clusters and triplet STEs formed by the ³P₁–¹S₀ transition of Sb³⁺. By regulating the Sb³⁺ concentration, the emission can be tuned from green to yellow and finally to orange, which would help to develop optically pumped white light-emitting diodes (WLEDs) with different photometric characteristics. Moreover, this dopant-induced extrinsic STE approach presents a new direction towards tuning the luminescence properties of 0D metal halides, and may find application in environmentally-friendly, high-performance metal halide light emitters.

As a promising way to modulate the photoluminescence properties and stability of perovskites and perovskite variants, doping has attracted wide attention in the field of optical and optoelectronic applications. In this work, a series of all inorganic lead-free Sb³⁺-doped Cs₂ZrCl₆ vacancy-ordered perovskite variants were prepared by the hydrothermal method, and the Sb³⁺-doping leads to singlet and triplet state emissions, which are strongly dependent on the temperature and surrounding molecular environment. Furthermore, efficient energy transfer can be observed from self-trapped excitons (STEs) of [ZrCl₆]²⁻ octahedra to dopant Sb³⁺. Our results will shed light on the ns² Sb³⁺-ion-doping-induced emissive mechanism and expand the understanding of the optoelectronic properties of the perovskite variant family.