About: Mechanochromic luminescence

Mechanochromic luminescence (ML) references to intensity and/or color changes of (solid-state) luminescent materials induced by mechanical forces, such as rubbing, crushing, pressing, shearing, or smearing. Unlike "triboluminescence" which does not require additional excitation source other than force itself, ML is often manifested by external photoexcitation such as a UV lamp. The most common cause of ML is related to changes of intermolecular interactions of dyes and pigments, which gives rise to various strong (exciton splitting) and/or weak (Forster) excited state interactions. For example, a certain boron complex of sunscreen compound avobenzone exhibits reversible ML. A recent detailed study suggests that ML from the boron complex consists of two critical coupled steps: 1) generation