An ideal anti-counterfeiting technique has to be inexpensive, mass-producible, nondestructive, unclonable and convenient for authentication. Although many anti-counterfeiting technologies have been developed, very few of them fulfill all the above requirements. Here we report a non-destructive, inkjet-printable, artificial intelligence (AI)-decodable and unclonable security label. The stochastic pinning points at the three-phase contact line of the ink droplets is crucial for the successful inkjet printing of the unclonable security labels. Upon the solvent evaporation, the three-phase contact lines are pinned around the pinning points, where the quantum dots in the ink droplets deposited on, forming physically unclonable flower-like patterns. By utilizing the RGB emission quantum dots, full-color fluorescence security labels can be produced. A convenient and reliable AI-based authentication strategy is developed, allowing for the fast authentication of the covert, unclonable flower-like dot patterns with different sharpness, brightness, rotations, amplifications and the mixture of these parameters.

High-performance quantum dot light-emitting diodes (QLEDs) are being considered as a next-generation technology for energy efficient solid-state lighting and displays. InP QLEDs are the most promising alternative to the toxic CdSe QLEDs. Unlike the problems of poor hole injection in CdSe-based QLEDs, highly delocalized electrons and parasitic emissions are serious problems in green-emitting InP QLEDs. The loss mechanism and device physics in InP QLEDs have not been sufficiently studied since the first report of InP QLED in 2011. This Focus Review summarizes the recent efforts on improving the performance of InP QLEDs from the perspectives of core/shell structures to optimization of carrier transport layers. It is our intention to conduct a review as well as clarify some previous misunderstandings regarding the device physics in InP QLEDs and to provide some insights for the possible solutions to the challenging problems in InP QLEDs.

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InP quantum dots (QDs) are emerging as promising materials for replacing cadmium‐based QDs in view of their heavy metal‐free and tunable luminescence. However, the development of InP QD materials still lags due to the expensive and flammable phosphorus precursors, and also the unsatisfactory repeatability caused by the fast nucleation rate. Adopting lowly reactive P precursor aminophosphine can overcome this issue, but their low photoluminescence quantum yield (PLQY) and widening line widths do not apply to the practical application. Through engineering, the core‐shell structure of QD, significantly promoted green emissions of QDs were obtained with PLQY of 95% and full width and half maximum (FWHM) of 45 nm, which demonstrated the highest PLQY record obtained from the aminophosphine system. Moreover, due to the residue halogen atoms on the QD surface as inorganic ligands to prevent further oxidization, these InP QDs demonstrated the ultra‐long operational lifetime (over 1000 h) for QDs based color enhancement film. By optimizing the device structure, an inverted green InP quantum dot light‐emitting diode (QLED) with external quantum efficiency (EQE) of 7.06% was also demonstrated, which showed a significant promise of these InP QDs in highly effective optoelectronic devices.

As the concerns about using cadmium-based quantum dots (QDs) in display are growing worldwide, InP QDs have drawn much attention in quantum dot light-emitting diodes (QLEDs). However, pure blue InP based QLED has been rarely reported. In this work, first of all, pure blue InP/ZnS QDs with emission wavelength of 468 nm and quantum yield of 45% are synthesized. Furthermore, zinc oleate and STOP are used as precursors to epitaxially grow the second ZnS shell. The residual zinc stearate reacted with STOP to form ZnS shell, which increased the thickness and stability of QDs. Moreover, as the residual precursor of zinc stearate is removed, the current density increased from 13 mA cm −2 to 121 mA cm −2 at 8 V for the hole only device. External quantum efficiency increased from 0.6% of InP/ZnS QLED to 1.7% of InP/ZnS/ZnS QLED.

The formation of Cu2SnSe3 tetrapod nanocrystals is reported using a hot injection colloidal synthesis. The ternary copper chalcogenide nanocrystals nucleate with a cubic core with four short wurzite arms.

Printable perovskite quantum dot (QD) ink is very important for achieving high quality coffee ring-free fluorescent microarrays for different kinds of emerging perovskite optoelectronic applications using inkjet printing.

Perovskite materials serve as promising candidates for display and lighting due to their excellent optical properties, including tunable bandgaps and efficient luminescence. However, their efficiency and stability must be improved for further application. In this work, quasi‐two‐dimensional (quasi‐2D) perovskites embedded in different polymers are prepared by inkjet printing to construct any luminescent patterns/pictures on the polymer substrates. The optimized quantum yield reaches over 65% by polyvinyl‐chloride‐based quasi‐2D perovskite composites. In addition, as‐fabricated perovskite−polymer composites with patterns show excellent resistance to abrasion, moisture, light irradiation, and chemical erosion by various solvents. Both quantum yield and lifetime are superior to those reported to date. These achievements are attributed to the introduction of the PEA+ cations to improve the luminance and stability of perovskite. This patterned composite can be useful for color‐conversion films with low cost and large‐scale fabrication.