RIKEN Marca Nuovo Progresso in Ultra-grandangolare Temperatura Intervallo (-180~240 grado ) Blu Fase Liquido Cristallo Laser

Blue-phase liquid crystals (BPLCs) lasers, with their low laser threshold, multi-stimulus response, multi-directional emission and real-time reconfigurability, have great application prospects in sensing, display and anti-counterfeiting. Currently, the research on blue phase liquid crystal lasers includes the tunability of the laser wavelength under external stimuli (e.g., light, electricity, heat, force, etc.), and the narrow temperature window of the BPLCs themselves has led to an increasing interest in the study of wide-temperature domain BPLCs lasers. The adoption of polymer stabilization systems has successfully broadened the temperature range of BPLCs to 500 degree , which also leads to the corresponding broadening of the temperature range of BPLCs lasers. However, compared with other organic lasers, the random crystallization of small molecules of the mobile phase in BPLCs at low temperatures and the poor compatibility between the dye and the system make it challenging to emit lasers below 0 degree in BPLCs. Moreover, the working mechanism of BPLCs lasers at low temperatures is still unclear. This severely limits the potential applications of BPLCs lasers in other low-temperature environments such as polar, deep ocean, and space. Therefore, the design of suitable BPLCs systems to meet good system compatibility and low-temperature antifreeze is important for the development of low-temperature BPLCs lasers.
In order to solve the above problems, the team of academician Jiang Lei and researcher Wang Jingxia from the Center for Bionanomaterials and Interface Science of the Institute of Physics and Chemistry, Chinese Academy of Sciences, prepared polymer-stabilized blue-phase liquid crystals with a wide range of temperatures (-190 degree ~360 degree ) in their previous work (Nat. Commun. 2021, 12 (1), 3477.); by adjusting the band gap centers and dye patterns of the blue-phase liquid crystals, we have been able to achieve the same results. By adjusting the prepared blue-phase liquid crystal bandgap center, dye ordering parameter, resonance cavity quality and pump energy, controlled one-to-four-mode surface emission lasing has been achieved in the resonance cavities of dye-doped blue-phase liquid crystals (C6-BPLCs) (Adv. Mater. 2022, 34 (9), 2108330.); the prepared blue-phase liquid crystals are used as templates for the preparation of highly resolved multicolor blue-phase liquid crystals. Using the prepared blue liquid crystals as templates, high resolution multi-color blue liquid crystals were prepared (Adv. Funct. Mater. 2022, 32 (15), 2110985.); and by regulating the polymer content of the blue liquid crystals, the polymer scaffolding system of the blue liquid crystals was obtained, and the temperature range of the BPLCs was extended to 25~230 degree (Adv. Mater. 2022, 34 (47), 2206580.). Mater. 2022, 34 (47), 2206580.
Recently, the research team has successfully realized a wide laser temperature range ({{0}} degree ) below 0 degree by rational system selection and design, reducing the random crystallization of small liquid crystal molecules at low temperatures by all-polymerization, and selecting chain-flexible liquid crystal monomers (RM105) and dye molecules (DCMs) to improve the compatibility of the system. It was shown that the all-polymer BPLCs exhibited a narrow laser linewidth (0.0881 nm) and low laser threshold (37 nJ/pulse) due to good system compatibility; meanwhile, the all-polymerized system increased the photo-thermal stability of the samples, including sufficient reflectance/fluorescence signals, suitable quantum yields and fluorescence lifetimes, matched reflectance and fluorescence spectra, stable BPLCs fabrication and high decomposition temperature, which enabled the samples to emit laser light in -180-240 degree . In addition, the variation rules of the laser wavelength and threshold of BPLCs at low temperature (<0 ℃) are revealed for the first time, i.e., red-shifted laser wavelength and increasing laser threshold with decreasing temperature, resulting in a red-shifted laser wavelength and a "U"-shaped laser threshold in -180~240 ℃. These unique laser behaviors are related to the temperature-dependent anisotropic deformation of the BP lattice (-180-0 ℃: BPI lattice contracted along the (110) direction; 0-26.7 ℃: almost unchanged BPI lattice; 26.7-240 ℃: BPI lattice accelerated to expand along the (110) direction). This work not only opens the door to low-temperature BPLCs, but also provides important insights into the design of novel organic optical devices.
The results are presented as Super-wide Temperature Lasers Spanning from -180 degree to 240 degree based onFully-polymerized Blue Phase Superstructures, published in Advanced Materials.
L'autore corrispondente dell'articolo è il Dott. Jingxia Wang dell'Istituto di Fisica e Chimica, Cinese della Accademia delle Scienze. Yujie Chen, un dottorando presso della IUPAC, CAS, era il primo autore. Mr. Jing Li e Mr. Feng Jin della IUPAC ha aiutato la caratterizzazione laser delle cristalli liquidi della fase blu, Prof. Lei Shi dal Dipartimento di Fisica, Fudan Università ha aiutato la caratterizzazione della banda fotonica di i cristalli liquidi della fase blu, e Accademico Lei Jiang dell'Istituto di Fisica e Chimica, Cinese Accademia delle Scienze, fornita guida professionale e assistenza per questo studio.
Questa ricerca è stata sostenuta da la Fondazione Nazionale Scienza Naturale della Cina e del Programma Olandese di Ricerca della Accademia Cinese delle Scienze.

Figura 1. Struttura chimica e caratterizzazione di BPLC completamente polimerizzati. a) Formularie chimiche strutturali delle sostanze utilizzate nei campioni completamente polimerizzati di coloranti drogati; b) diagramma schematico degli cambiamenti microstrutturali degli campioni nel -180 - 240 grado laser temperatura dominio; c) TEM plots; d) Kossel plots; Temperatura e) Riflettanza spettri e f) fluorescenza di i campioni di -180 - 240 grado ; g) laser lunghezza d'onda versus temperatura; h) confronto del Presentare Lavorare con la Gamma di Temperatura Operativa Di Laser Liquido Cristalli Fase Blu In La Letteratura.

Figure 2. Comparison of the performance of this all-polymer system with other systems and dye compatibility test. a) Comparison of the laser temperature range; b) Comparison of the laser threshold at room temperature; c) Dye solubility test under POM c1) 90.0 mg RM105 + 4.5 mg DCM; c2) 90.0 mg C6M + 4.5 mg C6, at 120 degree . This indicates that DCM has better compatibility with RM105. d-f) Theoretical calculations of cohesive energy density (CED), experimental system: RM105 + RM257 + DCM; control system: C6M + C6. The experimental system has a larger CED and solubility parameter (δ) than the control system, which suggests that the all-polymer system has better compatibility than C6M + C6. g) D) Theoretical calculations of DCM, RM105 + 4.5 mg DCM; c2) 90.0 mg C6M + 4.5 mg C6 at 120 degree . (g) DSC plot, there is only one glass transition temperature (Tg=26.7 degree ) for the all-polymer sample, while there is not only a Tg (-42.94 degree ), but also a crystallization peak (Tc=-24.95 degree ) and a phase transition peak of the unpolymerized component (TBP=77.35 degree ) for the sample with a polymerization degree of 25 wt%. (TBP= 77.35 degree ).
Figura 3. Proprietà laser dei campioni all-polymers. a-b) Emissione spettri, -180-240 grado ; c-d) FWHM del laser a temperatura ambiente; e) Laser soglia a ambiente temperatura; f) Soglia versus temperatura in a "U " forma.

Figura 4. Proprietà fototermica analisi di tutto-polimero campioni. a) Analisi termogravimetrica; b-d) In situ variabile temperatura XRD; e) Posizioni relative di riflessione picchi e fluorescenza picchi a diverse temperature; f) Riflessione centro lunghezza d'onda/riflessione intensità versus temperatura; Temperature variabili g) Quantistica rendimenti e h) Fluorescenza vite; i) In situ variabile temperatura POM grafici; j) In situ variabile temperatura angolare risolta spettri ( riflessione modalità).

Figura 5. In-situ Kossel variazione durante temperatura cambiamento di tutto-polimero campioni. a) Kossel grafici; b) Kossel grafici / BP reticolo versus temperatura; c) Kossel centro raggio circolare (R) e riflessione centro lunghezza d'onda (λ) versus temperatura (T).

Figura 6. Cambiamenti microstrutturali e altre proprietà laser di tutto polimero campioni durante temperatura cambiamento. a) Cambiamenti del BP reticolo a diverse temperature. a1) BPI reticolo contratto lungo (110); a2) quasi invariato BPI reticolo; a3) accelerato espansione di BPI cristalli lungo (110); b) laser emissione in tre direzioni ortogonali di x, y, e z, pompa energia: 0. 205 μJ/pulse; c) test di polarizzazione del laser, L/RCP: paura%2sinistra circolare polarizzata luce, pompa energia: 0.205 μJ/pulse. pompa energia: 0.205 μJ/pulse.