Mechanoluminescence Color Conversion by Spontaneous Fluorescent‐Dye‐Diffusion in Elastomeric Zinc Sulfide Composite

Abstract

wileyonlinelibrary.comtechnologies because ML can be generated by all mechanical vibrations occurring in nature. [ 3 ] Elastico-ML, luminescence by elastic deformation, has been mainly used for advanced applications because of its potential durability. [ 4,5 ] Various approaches have been proposed for using ML in sensor applications, mainly for visualizing crack propagation and for stress distribution. [5][6][7][8][9][10] Recently, the polydimethylsiloxane (PDMS)-supported zinc sulfi de (ZnS) composite structure has received considerable attention [ 3,[11][12][13][14][15][16][17] because of its durable [ 15,16 ] and color-tunable [ 3,17 ] ML characteristics. Such PDMS composites are very attractive owing to their easy fabrication, mechanical robustness, and low cost. Notably, from the viewpoint of application, the various color expression technologies could broaden the MLapplication fi elds. To date, many papers have been published reporting various inorganic compounds with color of ultraviolet, [ 18 ] blue, [ 19,20 ] green, [ 21,22 ] orange, [ 23 ] and red. [24][25][26] Alternative methods for ML color-tuning have also been proposed; the tuning characteristics were obtained by mixing different colored ML particles [ 17 ] or by changing the dopant concentration. [ 27 ] However, the strategies of previous reports have focused on color-tuning of ML material itself through newly developed inorganic ML compounds. In this paper, we introduce a new strategy for the color manipulation of ML by fl uorescent dyes physically combined with existing ML materials.Color conversion using wavelength-converter materials has been widely applied in light-emitting devices such as organic/ inorganic light-emitting diodes [28][29][30] and dye lasers. [31][32][33] Several types of wavelength-converter materials are available, such as phosphors, semiconductors, and dyes. [ 28 ] In particular, organic fl uorescent dyes are promising for the development of low-temperature solution-processed devices because organic dyes are usually soluble in various solvents. Hence, if energy-transferrable organic fl uorescent dyes with different luminescence and absorption spectra can be combined with ML materials, broad-color manipulation technology would be promoted because various emission colors can be produced depending on the dyes selected.Color conversion, long-wavelength light emission by absorbing shortwavelength light, is an attractive approach for developing a broad-color expression technology and is widely used in solid-state lighting, dye-lasers, and colorful displays. Up to now, many papers have been published reporting various mechanoluminescent materials emitting color of ultraviolet, blue, green, orange, and red. However, the strategies of previous reports have focused on color-tuning of mechanoluminescent material itself through newly developing inorganic mechanoluminescent compounds. Here, a new strategy for the color manipulation of mechanoluminescence (ML) is introduced by physically combining fl uorescent dyes with existing mechanol...

Alkyl Chain Introduction: In Situ Solar‐Renewable Colorful Organic Mechanoluminescence Materials

“…[11,12] This is due to their strong tendency for self-assembly and cluster formation (for example,g lycerophospholipids bilayers [13] in cell membrane,a nd interdigitation in poly(3-hexylthiophene-2,5-diyl), P3HT [14] ). [6] In this strategy,the carbazolyl unit was chosen as the ML unit because some of its derivatives exhibit efficient ML. [15] Inspired by this and as shown in Figure 1, as oft alkyl chain with appropriate length was introduced into an Ncarbazole ML unit.…”

“…[3] Furthermore,M Lm aterials can be also utilized in advanced sensors to enable wireless,insitu, real-time,and distributed (WIRD) damage,stress,and impact sensing in civil and aerospace systems. [5,6] However,these inorganic systems with efficient ML are generally prepared at very high temperature,w hich limits their applications.I nc ontrast, organic ML materials show convenience of preparation and various ML properties.P urely organic ML materials have attracted much attention recently,b ecause of simple organic compounds with bright ML in daylight have been reported constantly in recent years. [5,6] However,these inorganic systems with efficient ML are generally prepared at very high temperature,w hich limits their applications.I nc ontrast, organic ML materials show convenience of preparation and various ML properties.P urely organic ML materials have attracted much attention recently,b ecause of simple organic compounds with bright ML in daylight have been reported constantly in recent years.…”

A Review of Mechanoluminescence in Inorganic Solids: Compounds, Mechanisms, Models and Applications

“…Unfortunately, the efficiency of this process was not reported, which may impose limits on the application of ML phosphors as display materials in cases where wind is the only excitation source. Meanwhile, the tuning of emission spectra can be achieved by mixing different ratio of ZnS:Mn/ZnS:Cu [127] or using dyes as spectrum converter based on energy transfer [126]. …”

Elastic instability induced mechano-responsive luminescence for super-flexible strain sensing

“…Examples can be found, such as using the mechanical force to change the arrangement of luminescent molecular which can lead to the optical switching response [8,9]. Such properties could potentially be facilitated for sensing applications integrated with optical detection systems, such as photo-diodes, fluorescence microscopes (e.g.…”