Boosting the luminescence performance of magneto-mechano-luminescence devices by leveraging self-generated electric potentials

Abstract

The reported research on Mechano-luminescence (ML) has primarily focused on enhancing luminescence by optimizing mechanical energy for luminescence by employing various structural deformations of ML composites in response to mechanical stress. In contrast, this study demonstrates the innovative use of ambient magnetic fields to drive a lighting device without any external electrical source. This approach involves the simultaneous application of magnetically induced mechanical vibrations and a self-generated electric potential in the same periodic time. Our magnetically driven lighting device comprises a sheet-shaped ML composite consisting of ZnS:Cu particles embedded within a polydimethylsiloxane (PDMS) elastomer, along with a magnetically vibrating cantilever beam incorporating a 32-mode piezoelectric single crystal fiber composite (SFC). This structure forms a magneto-mechano-electric (MME) generator, capable of simultaneously applying mechanical stress and electrical potential to the ML composite under second harmonic bending vibration. Notably, the MME generator in second harmonic vibration mode responds to ambient magnetic field oscillations, inducing electric potential within the SFC. When the projection part of the MME generator contacts the ML composite, the induced electric potential supplies additional electrons to the ML material. This influx of electrons facilitates greater recombination within the ML composite, thereby enhancing luminescence efficiency. Our results indicate a 240 % improvement in luminescence efficiency when both mechanical and electrical energies are applied simultaneously compared to when only mechanical energy is utilized. When tested in a real-world environment at 60 Hz, the magnetically driven lighting device emits visible light without requiring any additional electrical power source.