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Abstract The development of white organic light-emitting diodes (WOLEDs) holds great promise for the production of high-color-quality lighting sources. High quantum efficiencies for the conversion of electrical energy to light have been realized. The color stability and color-rendering index (CRI) become bottleneck for the commercial application of WOLEDs. Here, we employed a metal-free dimerization of 1‑phenyl‑3,5‑diamine‑triazine (DPDT) as a single non-doped emitter in WOLEDs, that exhibits mild efficiency roll-off while maintaining CRI of 92. This high CRI is attributable to the DPDT with efficient monomer and excimer emission, which together emit a relatively wide spectrum that nearly covers the entire range of visible light. The formation of the excimer can make the emission color of single-emitter based WOLEDs tunable with the applied bias over a wide range from blue to pure white. Highlights • The metal-free dimerization of 1-phenyl-3,5-diamine-triazine (DPDT) materials were synthesized. • The emission color can be tuned over a wide range from blue to pure white. • The resulting color tunable WOLEDs achieves mild efficiency roll-off while maintaining CRI of 92. [ABSTRACT FROM AUTHOR]

We have developed a high color rendering index (CRI) top-emitting white organic light-emitting diode (TWOLEDs) using single emitter by enhancing the yellow-green part between the monomer and excimer emission of platinum [1,3-difluoro-4,6-di(2-pyridyl)benzene] chloride via microcavity effect. Resonant wavelengths can well-tuned by adjusting the thickness of the hole transport layer to modify the optical cavity length. The TWOLEDs exhibits four-peak spectra at 480, 512, 556, and 600 nm with maximum color rendering index of 83 and full half-maximum width of 200 nm. Meanwhile, the chromaticity of TWOLEDs is quite stable, showing slight Commission Internationale deL'Eclairage coordinate shifts of (±0.005, ±0.004) over the driving voltage range of 4–10 V. [Display omitted] • High color rendering index and chromaticity stable top-emitting white OLEDs with single emitter. • Four peak emission are achieved by combining monomer, excimer emission and resonant cavity. • Weak microcavity white OLEDs were investigated and modelled. • The device emission shows a Lambertian-like characteristic. [ABSTRACT FROM AUTHOR]

Abstract: In this paper, we introduce a modified inverted microscope system in which an objective with high NA (0.95) is located under high-vacuum conditions, and a time-correlated single photon counting system is used along with a modified photomultiplier tube for the characterization of single emitters under high-vacuum conditions. The modified inverted microscope system is designed to be simple, compact, and easy to handle. As an example, the optical properties of individual colloidal semiconductor nanocrystals (CdSe/ZnS) were studied by using these systems. [Copyright &y& Elsevier]

A thermally activated delayed fluorescence (TADF) emitter, named 4CzDBN , was developed with benzonitrile and carbazole groups. It's highly symmetrical and elongated framework was intentionally devised to form strong intermolecular π-π interactions in the condensed state. Through a series of detailed studies on the photophysical properties, single crystal structures and theoretical calculations of 4CzDBN , the impact of molecular structure regulation on excited state properties were investigated thoroughly. Finally, organic light-emitting diodes (OLEDs) utilizing 4CzDBN as the single emitter realized full-color emission from sky blue (480 nm) to orange red (580 nm) at different doping concentrations, as the first single-emitter full-color OLED. Image 1 • A novel molecular design strategy was proposed, 4CzDBN structure with highly symmetrical and elongated skeleton was deliberately devised to form strong intermolecular π-π interactions. • Through simply adjusting the doping concentrations of 4CzDBN in thin films, the maximum emission can be tuned from 494 to 554 nm. • The investigation on the single crystal structures and theoretical calculations confirm the underlying mechanism that luminescent regulation can be achieved by intermolecular π-π interactions. • 4CzDBN based single-emitter OLEDs realized full-color emission (from 480 nm to 580 nm) via tuning the doping concentrations for the first time ever. [ABSTRACT FROM AUTHOR]