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Organic ultra-long room temperature phosphorescence (OURTP) has been widely used in applications including encryption and anti-counterfeiting. However, little research has focused on circularly polarised luminescence (CPL) with RTP materials. In order to construct circularly polarised room temperature phosphorescent (CP-RTP) materials with highly efficient luminescent properties, we report on the synthesis of a novel chiral phosphorescent molecule and its immobilization in a dynamically crosslinked Vitrimer film. The lifetime and quantum yield of the green persistent RTP are 895 ms and 9.70%, respectively, and the dissymmetry factor (glum) is up to 0.014. In addition, it exhibits good thermal stimulus response properties, which remain unchanged under repeated multiple cycles of heating/cooling, and it can be further widely used in the field of encryption of optical information and other applications. [ABSTRACT FROM AUTHOR]

Electrically driven multi-stable cholesteric liquid crystals can be used to adjust the transmittance of incident light. Compared with the traditional liquid crystal optical devices, the multi-stable devices only apply an electric field during switching and do not require a continuous electric field to maintain the various optical states of the device. Therefore, the multi-stable devices have low energy consumption and have become a research focus for researchers. However, the multi-stable devices still have shortcomings before practical application, such as contrast, switching time, and mechanical strength. In this article, the latest research progress on electrically driven multi-stable cholesteric liquid crystals is reviewed, including electrically driven multi-stable modes, performance optimization, and applications. Finally, the challenges and opportunities of electrically driven multi-stable cholesteric liquid crystals are discussed in anticipation of contributing to the development of multi-stable liquid crystal devices. [ABSTRACT FROM AUTHOR]

Salt hydrate-based phase-change materials are considered promising for future heat storage applications in residential heating/cooling systems. Smooth phase transition from the liquid to solid phase and vice versa is essential for effective heat exchanger; however, supercooling in salt hydrates delays the onset of liquid–solid phase transition. We investigate the molecular level mechanism of supercooling in sodium sulfate decahydrate (SSD). SSD is a complex salt hydrate whose properties are governed by electrostatic forces that include pure Coulombic interactions as well as hydrogen bonds. Experimentally, we examine the importance of a nucleator in reducing supercooling temperatures. We investigated the effect of various mass concentrations of a borax nucleator on a decrease of supercooling temperatures. Molecular dynamics simulation techniques are used to obtain a basic understanding of supercooling in SSD. We observe that by introducing borax as a nucleator, there is a decrease in the supercooling temperature before nucleation. Our molecular dynamics simulations show that long-range electrostatics between sodium and sulfate ion pairs and that with polar water molecules is responsible for delayed nucleation in SSD that results in supercooling, and also, dynamics of charged molecules slows down. The lack of crystallization leads to amorphous structures in supercooled SSD. [ABSTRACT FROM AUTHOR]

Organic room temperature phosphorescence (RTP) materials with stimuli-responsive properties show great potential for application in information security and optoelectronic devices. Herein, we present a convenient and effective method to trigger and enhance the yellow RTP of small molecular weight host–guest materials by grinding and adding water. The phenomenon of grinding-excited RTP is attributed to the efficient energy transfer from the host to the guest molecules. After the introduction of water, the phosphorescence intensity of the doped material significantly increases, and the phosphorescence quantum yield (PhQY) increases to more than double. The enhancement is attributed to the formation of intermolecular hydrogen-bonding networks. The hydrogen-bonding networks can confine the molecular motion effectively and suppress non-radiative transitions. By virtue of the unique and sensitive water response characteristics of a doped material, anti-counterfeiting printing and humidity detection based on this material have been demonstrated. [ABSTRACT FROM AUTHOR]