Renaissance of Organic Triboluminescent Materials

Abstract

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.

Organic luminescent materials: The concentration on aggregates from aggregation‐induced emission

“…Inspired by the great promotion of AIE effect in the development of bright ML luminogens, more and more scientists devoted themselves into this field. [65][66][67][68][69][70][71][72] Within just a few years, a series of bright ML materials have been developed with the similar strategy. Based on them, the internal mechanism was carefully studied and deeply understood, especially for the relationship between molecular packing and ML emission ( Figure 13).…”

Miracles of molecular uniting

“…More interestingly, light emission from new excitation process can be realized in molecular aggregates. Unlike the normal luminescence from irradiation or electric driving, some organic solids exhibit attractive emissions upon mechanical stimuli, defined as ML or triboluminescence (TL) [40,41]. Generally, the multi-mechanosensitivity of certain ML materials is related to the lattice behavior, such as the molecular arrangement in the solid state.…”

Triboluminescence of a new family of CuI–NHC complexes in crystalline solid and in amorphous polymer films

“…[1][2][3] A modern triboluminescent observation is the light emission that occurs upon the peeling of an adhesive tape. Currently, TL materials are considered as promising targets for the development of damage sensors [4][5][6][7] or other types of "smart" materials that can nd application in information storage or health care devices. 8 Among known TL coordination compounds, complexes of rare earth elements, Eu III and Tb III , are the most widely known.…”