Metal halide perovskite light-emitting diodes (LEDs) have achieved great progress in recent years. However, bright and spectrally stable blue perovskite LED remains a significant challenge. Three-dimensional mixed-halide perovskites have potential to achieve high brightness electroluminescence, but their emission spectra are unstable as a result of halide phase separation. Here, we reveal that there is already heterogeneous distribution of halides in the as-deposited perovskite films, which can trace back to the nonuniform mixture of halides in the precursors. By simply introducing cationic surfactants to improve the homogeneity of the halides in the precursor solution, we can overcome the phase segregation issue and obtain spectrally stable single-phase blue-emitting perovskites. We demonstrate efficient blue perovskite LEDs with high brightness, e.g., luminous efficacy of 4.7, 2.9, and 0.4 lm W-1 and luminance of over 37,000, 9,300, and 1,300 cd m-2 for sky blue, blue, and deep blue with Commission Internationale de l’Eclairage (CIE) coordinates of (0.068, 0.268), (0.091, 0.165), and (0.129, 0.061), respectively, suggesting real promise of perovskites for LED applications.

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This paper provides a new insight into the fundamentals of plasma medicine: The definition of “plasma dose.” Based on the dominant role of reactive oxygen nitrogen species (RONS) in plasma biological effects, we first propose the equivalent total oxidation potential (ETOP) as the definition of plasma dose. The ETOP includes three parts: the item H, which is the ETOP of the RONS generated by plasma; the item T, which is associated with the reactive agents unrelated to RONS, such as UV/vacuum ultraviolet (VUV) emission of plasma; and the item f(H,T), which is related to the synergistic effects between H and T factors. To evaluate the feasibility of the ETOP as a plasma dose, the bacterial reduction factor (BRF), which is the log reduction of bacteria colony-forming units, is selected as the indicator of the plasma biological effect. A model establishing the relationship between the ETOP and BRF is presented. For the first try of this paper, a linear relationship between the lgETOP and BRF is assumed. The model is initially validated by the published data from the literature. Further simulation and experiment are also conducted, and the positive correlation between the ETOPs and BRFs in the model again suggests that the ETOP could be a reasonable solution as the plasma dose. Finally, the prospects for improving the ETOP, such as including RONS generated in liquid phase, evaluating the weight factor of each type RONS, and involving the effect of electrons, ions, and UV/VUV, are discussed.

SummaryPlasma is an ionized gas that consists of positively and negatively charged particles, neutral atoms, and photons. Recent developments in plasma sources have made it possible to generate room-temperature plasma in the "open air", thus enabling the application of plasma in vivo. Using nonthermal plasma, active agents can be efficiently delivered to target cells without creating thermal damage. Also known as cold atmospheric pressure plasma (CAP), nonthermal atmospheric pressure plasma offers innovative medical applications. In this context, it has also gained wide attention in the field of dermatology. The complex and variable mixture of active agents in plasma -predominantly reactive oxygen and nitrogen species (ROS, RNS) -can control or trigger complex biochemical reactions, achieving the desired effects in a dose-dependent manner. The objective of the present review is to present potential applications of plasma in dermatology and analyze its potential mechanisms of action.

Recently, cold atmospheric pressure plasmas (CAPs) have provided many new opportunities in dermatology by providing a multimodal action of reactive agents (RA). This review critically examines the generation, transport, and physical effects induced by CAPs in dermatologic treatments. We introduce the most suitable plasma sources, which provide a multitude of physical effects on the skin without any electric or thermal shocks. The mechanisms of generation and transport of the key reactive species are introduced and examined from the viewpoint of their applications in dermatology. Special attention is paid to study the “plasmaporation” effect, which enables RA penetration through healthy and damaged skin. Plausible physical mechanisms involved in the CAP treatment of some of the most common skin diseases are analyzed.