Mukherjee Sanjoy, Thilagar Pakkirisamy
Mitsubishi Chemicals Center for Advanced Materials, University of California Santa Barbara, CA, 93106, USA.
Department of Inorganic and Physical Chemistry, Indian Institute of Science, Bangalore, 560012, India.
Angew Chem Int Ed Engl. 2019 Jun 11;58(24):7922-7932. doi: 10.1002/anie.201811542. Epub 2019 Mar 12.
Solid-state luminescence of organic dyes is an elusive frontier, and understanding and designing solid-state stimuli-responsive materials is not trivial. "Mechanoluminescence" (ML) or "triboluminescence" (TL), which is associated with fracture or force-initiated luminescence from a material, is currently attracting new interest. Fracturing the surfaces of organic crystals ordered in noncentrosymmetric space groups can electronically excite the surface and neighboring molecules through piezo- or pyroelectric effects, and this can result in luminescence when the molecules relax back to their ground states. The combined duration of these two consecutive phenomena leads to force-generated luminescence or TL. Although TL has been known for a very long time, examples of TL-active materials are scarce, but are increasing as synthetic and characterization procedures develop. The question is now whether the relatively rare phenomenon of TL needs to be reevaluated to obtain a broader understanding of the subject.
有机染料的固态发光是一个难以捉摸的前沿领域，理解和设计固态刺激响应材料并非易事。与材料断裂或力引发的发光相关的“机械发光”（ML）或“摩擦发光”（TL）目前正引起新的关注。在非中心对称空间群中有序排列的有机晶体表面发生断裂时，可通过压电或热电效应使表面及相邻分子发生电子激发，而当分子弛豫回到基态时，这会导致发光。这两个连续现象的持续时间总和导致力致发光或TL。尽管TL已为人所知很长时间，但具有TL活性的材料实例稀少，但随着合成和表征方法的发展，此类实例正在增加。现在的问题是，是否需要对相对罕见的TL现象进行重新评估，以便更全面地理解这一主题。
