The solid-state photoluminescent quantum yield of triboluminescent materials

Ground rules defining design of triboluminescent (TL) materials are currently missing, in part since the triboluminescent efficiency is the product of the efficiency of excited-state formation and the efficiency of radiative relaxation from these excited-states. In order to de-couple these two processes, we have measured, for the first time, the solid-state photoluminescent quantum yield of various triboluminescent materials. The measurements highlighted: (i) some triboluminescent materials possess near-optimised radiative yields; (ii) structurally similar triboluminescent compounds can exhibit widely varying yields and (iii) some triboluminescent materials, which appear to the eye as reasonably efficient, possess low radiative yields, allowing possible triboluminescent enhancement.