蓝相液晶技术的进步

为了解决蓝相液晶,特别是聚合物稳定蓝相液晶实用化所面临的瓶颈,业内人士对聚合物稳定蓝相液晶显示器的各个方面,例如：新的电极结构和形状、单体在聚合物网络结构中的分布、GTG响应时间和工作物理过程等方面作了许多研究,文章对此作了综合介绍。     

蓝相液晶光电特性研究

蓝相液晶由于其特有的扭曲双螺旋结构,具有快速响应特性与宏观上的光学各向同性。通过聚合物稳定的方法,可以提升其热稳定性,但是也导致了驱动性能下降,磁滞效应增强等问题。文章通过研究手性掺杂和聚合物网络对蓝相液晶材料体系的作用以及不同温度下的磁滞效应,探索蓝相液晶器件光电特性的影响因子,为改善蓝相液晶材料的光电特性提供理论上的支持。     

蓝相液晶网络聚合物及其应用进展

蓝相是一种通常介于各向同性态和胆甾相态之间的高手性液晶相态,由于其具有独特的光学各向同性、快速电场响应以及选择性反射波长等光学性能,因而在液晶显示、光学器件以及在可调谐的三维光子晶体等方面均具有良好的发展前景。近年来,蓝相液晶材料引起了国内外研究者的广泛关注。本文综述了蓝相液晶的发展历程、蓝相液晶网络聚合物的研究进展及其应用现状,讨论了蓝相材料在显示和微电子领域的应用局限性,最后总结了蓝相液晶和蓝相网络聚合物在先进功能材料设计和器件应用中的机遇和挑战。     

蓝相液晶晶体结构与结构色

蓝相液晶具有许多不同寻常的光学特性,如快速的响应速度(亚毫秒量级),可见光范围的布拉格反射,光学各向同性等。这些特性使得蓝相液晶在电光器件领域有着广泛的应用前景。近年来,除显示领域以外,蓝相液晶在聚合物蓝相液晶薄膜、晶格结构、结构色,以及可调谐方面取得了一系列新的进展。这些进展不仅深化了人们对蓝相液晶制备和基本结构认知,同时也极大扩展了其应用范围。本文侧重阐述近年来蓝相液晶在晶格结构以及结构色方面的研究进展。首先介绍蓝相液晶薄膜的制备方法和进展;其次介绍蓝相液晶晶格结构,包括单畴晶格、单晶晶格和结构色方面的研究进展;最后介绍可调谐的蓝相液晶晶格结构,主要包括电场、光场对蓝相晶格的调控作用。     

基于多重掺杂的高科尔常数聚合物稳定蓝相液晶

聚合物稳定蓝相液晶具有亚毫秒级响应速度,光学各向同性及无需配向工艺等特点,在显示及光子器件领域有广泛的应用。本文研究了一种基于聚合物稳定蓝相液晶的多重聚合物材料掺杂系统。聚合物稳定蓝相液晶的驱动电压可以通过掺杂N-乙烯吡咯烷酮(NVP)和聚苯胺氧化石墨烯(G-PANI)得到大幅度的降低。经过优化掺杂物的配比,多重掺杂的聚合物稳定蓝相液晶材料的科尔常数被提高了68%,并且不会对材料的响应时间、磁滞及残留双折射产生负面影响。     

聚合物稳定双频蓝相液晶的亚微秒电光响应

蓝相液晶由于其出色的电光性质在信息显示和光电子领域受到了广泛的关注，然而日益发展的信息技术对信息的传递、处理、存储速度提出了更高的要求。为了进一步强化蓝相液晶的快速电光响应优势，本文以双频向列相液晶为主体，掺杂聚合单体、手性剂、光引发剂等材料制备了聚合物稳定双频蓝相液晶，通过调节双段电压脉冲时长，实现了聚合物稳定双频蓝相液晶的快速电光调控，其电光调控的开关时间均小于500 ns。     

降低聚合物稳定蓝相液晶显示器驱动电压的一种方法

聚合物稳定蓝相液晶显示器存在驱动电压高和"磁滞效应"的缺点,是其应用之路上的难题。本文在深入研究蓝相液晶显示器中所使用的各种材料介电常数的基础上,结合电动力学中电介质中的电场和电位移之间关系的知识,解释了蓝相液晶显示器驱动电压高的原因为聚合物材料和绝缘层材料的介电常数远低于蓝相液晶材料的介电常数。研究中发现提高聚合物材料和绝缘层材料的介电常数,将会明显降低聚合物蓝相液晶显示器驱动电压。理论和模拟结果表明:当聚合物材料和绝缘层的介电常数达到蓝相液晶的平均介电常数,该聚合物稳定蓝相液晶显示器的驱动电压降低一半。研究结果将对聚合物稳定蓝相液晶显示器的产业化应用起到促进作用。     

蓝相液晶及其在微透镜器件中的应用

聚合物稳定蓝相液晶(PSBPLC)具有响应速度达到亚毫秒量级,偏振光独立及工艺无需取向工艺等特点,在显示技术及光电子器件领域有潜在的巨大应用空间。文章论述了PSBPLC微观相变模型、宏观克尔效应等特性。在此基础上,论述了蓝相液晶微透镜技术的发展。介绍了PSBPLC实现微透镜阵列的主要结构,包括圆孔电极的蓝相液晶透镜;曲面电极的蓝相液晶透镜;多电极蓝相液晶GRIN透镜;模式控制的蓝相液晶透镜,以及采用ZnO纳米棒为电极实现蓝相液晶透镜,对比了上述几种透镜的结构和特点。     

蓝相液晶对聚集诱导发光分子荧光性能的影响

为了拓宽蓝相液晶的应用范围,构建多功能化蓝相体系平台,本文将具有聚集诱导发光（AIE）特性的液晶TPEPPE引入蓝相液晶体系,围绕复合体系的荧光性能展开研究。一方面,系统研究并归纳了手性添加剂含量对蓝相液晶相转变行为和光子带隙位移情况的影响;另一方面,探究了蓝相液晶对AIE分子荧光性能的影响,提出了相关荧光增强效应的假说。实验结果表明,不同手性添加剂体系的蓝相Ⅱ的温域范围基本一致,且反射带隙随着温度的降低发生蓝移;而蓝相Ⅰ的温域与手性密切相关,体系中仅存在蓝相Ⅰ时,其反射带隙随温度的降低而红移。蓝相液晶体系对AIE分子有一定的荧光增强效应,并且在整个蓝相温域内,蓝相Ⅰ的反射带隙红移,体系的荧光强度明显增强。由此得出结论,TPE-PPE分子在一定程度上参与了蓝相液晶体系的自组装。由于TPE-PPE分子在双螺旋柱结构中的受限运动,导致其荧光强度增强。随着蓝相Ⅱ的消失和蓝相Ⅰ光子带隙的红移,更多TPE-PPE分子参与到双螺旋柱的自组装中,体系的荧光发射增强。     

不同单体配比对聚合物网络及聚合物稳定胆甾相液晶器件光电性能的影响

为了调节聚合物网络与液晶分子之间的相互作用,从而改善聚合物稳定胆甾相液晶(PSCLC)的光电性能,本文采用紫外光聚合诱导相分离法(PIPS)制备了聚合物稳定胆甾相液晶,通过控制2种单体RM257与BAB6的比例来改善器件性能。随着RM257含量的减少,聚合物网络由取向排列的纤维状结构向疏松不规整的交联状结构转变,形成的聚合物网络对液晶分子的锚定作用减弱,聚合物稳定胆甾相液晶的饱和电压降低,关闭时间增大。当RM257与BAB6质量比为1∶4时,聚合物稳定胆甾相液晶器件具有较好的对比度。     

Network Polydiacetylene Films: Preparation,Patterning, and Sensor Applications

The synthesis, characterization, and functionalization of polydiacetylene (PDA) networks on solid substrates is presented. A highly transparent and cross‐linked diacetylene film of DCDDA‐bis‐BA on a solid substrate is prepared first by tailoring the monomers with organoboronic acid moieties as pendant side groups and consequent drop‐casting and dehydration steps. Precisely controlled thermal curing plays a key role to obtain properly aligned diacetylene monomers that are closely packed between the boronic acid derived anhydride structures. A second cross‐linking, which occurs by polymerization of the diacetylene monomers with UV irradiation, induces a transparent to blue color shift. Accordingly, colored image patterns are readily available by polymerization through a photomask. The color change that takes place as a response to various organic solvents can be simply detected by naked eyes. The thermofluorescence change of PDA networks is demonstrated to be an effective method by which to obtain the microscale temperature distribution of thermal systems. The ease of film formation and stress‐induced blue‐to‐red color change with a simultaneous fluorescence generation features of the network structure should find a great utility in a wide range of chemical and thermal sensing platforms.     

脉冲激光刻蚀聚乙烯的蓝光发射

采用波长为1 064 nm的激光束在不同激光功率下刻蚀聚乙烯(PE,polyethylene)透明薄膜表面,与刻蚀前的PE相比较,在紫外灯照射下,刻蚀后的PE发出明显的蓝光.采用扫描电镜(SEM)荧光光谱和Raman光谱等方法对激光刻蚀前后样品的表面形貌、表面结构和组成进行分析.结果表明,激光刻蚀使PE表面形成C＝C双键,导致刻蚀后的PE发出明显的蓝光,激光强度的大小对PE表面物理性质和化学结构有重要的影响.     

偶氮分子掺杂对蓝相液晶选择性反射波长的影响

偶氮基团(—N=N—)在适当波长光的照射下,会发生可逆的顺反异构反应,这一反应中偶氮分子构型上的变化会影响到蓝相液晶中脆弱的晶格结构,并造成晶格参数的变化,进而影响到选择性反射波长的变化,甚至有时会造成蓝相相态的消失。文章合成并将几种偶氮化合物掺入手性向列相液晶中,再变温至BPI,对比了这几种偶氮化合物对蓝相液晶选择性反射波长的影响,从而得出更有实际使用价值的偶氮分子,在此基础上还从分子结构角度分析了产生差异的原因,为进一步的改进工作提供了方向。     

纳米氧化物光谱特性及其相关机理的初步分析

纳米氧化物粉体与常规氧化物粉体相比呈现出吸收峰发生红移、蓝移等特异性能。初步研究表明,纳米颗粒尺寸越小,这些特异效应越明显,有关纳米氧化物光谱特性的研究已成为当前纳米材料研究的热点之一;然而,其光谱特性机理尚无统一解释。通过对波谱吸收机理和纳米材料特性的综合考察和分析,以及结合具体纳米氧化物材料的讨论,给出了导致蓝移、红移的主要因素。     

Domain Distribution Management of Quasi-2D Perovskites toward High-Performance Blue Light-Emitting Diodes

Quasi-2D perovskites, as one of the promising materials applied in perovskite light-emitting diodes (PeLEDs), have attracted great attention for their superior semiconductor properties. The inherent multiquantum well structure can induce a strong confinement effect, which is especially suitable for blue emission. However, compared to their green counterparts, blue emitters constructed from quasi-2D perovskites are more sensitive to n domain distribution (where n represents the number of PbX₆ inorganic layers). Suffering from inefficient domain distribution management, blue PeLEDs now face a variety of negative issues, including color instability, multipeak emission, and poor fluorescence yield. In this review, the development of blue PeLEDs and the optical properties of quasi-2D perovskites are overviewed. Then, a classification and summary of strategies for domain distribution management are proposed. Finally, the challenges and potential directions of domain distribution management in quasi-2D perovskites are summarized. This review is expected to provide a comprehensive perspective and reference on domain distribution management toward efficient blue quasi-2D PeLEDs.     

High‐Quality Electrochromic Polythiophenes via BF3·Et2O Electropolymerization

Electrochemical polymerization in the strong Lewis acid, boron trifluoride ethylether (BFEE), has been used to prepare electrochromic polythiophene (PTh) and its derivatives: poly(3‐methylthiophene) (PMeTh), poly(3‐bromothiophene) (PBrTh), and poly(3,4‐dibromothiophene) (PDBrTh). The polymerization processes and properties of the resultant films are compared, where possible, to those carried out in traditional organic electrochemical solvents. The polymerization of these high oxidation potential thiophene monomers in BFEE yielded good‐quality, homogenous, and smooth electroactive and electrochromic films that could be repeatedly switched in common electrochemical solvents up to 240, 1380, 560, and 420 cycles for PTh, PMeTh, PBrTh, and PDBrTh, respectively, for 50 % retention of electroactivity. A colorimetric study of these films showed distinctive color changes between red and blue as they were switched between reduced and oxidized states. These findings allow the use of commercially available high oxidation potential thiophene monomers to provide electrochromic polymers, avoiding the use of other custom‐synthesized monomers.     

Rational Design of Supramolecular Conjugated Polymers Displaying Unusual Colorimetric Stability upon Thermal Stress

The colorimetric stability upon thermal stress of a series of conjugated polymer supramolecules prepared from 10,12‐docosadiyndioic acid (DCDDA)‐derived diacetylene monomers has been explored. Polydiacetylenes obtained from DCDDA‐bis‐mBzA 3 , containing m‐carboxyphenylanilido groups at the both ends of the monomer, were observed to be highly colorimetrically stable upon thermal stimulation. The blue color of a solution containing these polydiacetylene vesicles remains unchanged even when the vesicles were subjected to boiling water. The unusual colorimetric stability is further demonstrated by the observation that blue color persists until vesicles in ethylene glycol are heated to 140 °C. The nature of this unusual thermal stability was elucidated by using polydiacetylene supramolecules, prepared from analogs of DCDDA‐bis‐mBzA 3 . The presence of internal amide groups as well as aromatic interactions was found to be essential for the high colorimetric stability of the polydiacetylene supramolecules.     

有机染料在多孔铝中的发光研究

用电化学方法制备的多孔阳极氧化铝具有孔径大小均匀、相互平行、排列规则的微孔结构 ,可作为多种发光材料的透明基底 .以多孔铝为载体 ,将有机染料嵌入多孔铝孔中 ,获得有机染料固体镶嵌膜 ,测量了镶嵌膜的吸收光谱、光致发光谱 .镶嵌膜的吸收光谱和液相染料的吸收光谱基本一致 ,光致发光谱的发光峰位蓝移 ,发光强度降低 ,但光谱线型更趋于对称 .实验结果表明染料以单体形式存在于多孔铝中 .通过对衬底多孔铝进行一系列后处理 ,发现热处理和扩大多孔铝空隙率可以增强镶嵌膜的发光强度     

Blue Single‐Layer Organic Light‐Emitting Diodes Using Fluorescent Materials: A Molecular Design View Point

Since the beginning of organic light‐emitting diodes (OLEDs), blue emission has attracted the most attention and many research groups worldwide have worked on the design of materials for stable and highly efficient blue OLEDs. However, almost all the high‐efficiency blue OLEDs using fluorescent materials are multilayer devices, which are constituted of a stack of organic layers to improve the injection, transport, and recombination of charges within the emissive layer. Although the technology has been mastered, it suffers from real complexity and high cost and is time‐consuming. Simplifying the multilayer structure with a single‐layer one, the simplest devices made only of electrodes and the emissive layer have appeared as an appealing strategy for this technology. However, removing the functional organic layers of an OLED stack leads to a dramatic decrease of the performance and achieving high‐efficiency blue single‐layer OLEDs requires intense research especially in terms of materials design. Herein, an exhaustive review of blue emitting fluorophores that have been incorporated in single‐layer OLEDs is reported, and the links between their electronic properties and the device performance are discussed. Thus, a structure/properties/device performance relationship map is drawn, which is of interest for the future design of organic materials.