Piezoluminescence: Controlled direct conversion of mechanical energy into light
Abstract
Direct conversion of mechanical energy into light of specific wavelength will open a completely new domain for design of novel sensing systems. Imagine mechanical-strainpowered flexible displays. Light can be converted into mechanical strain through the photostriction effect, but the converse effect has been missing or weakly present in nanostructured materials. The goal of this program is to discover physical principles that lead to controlled Piezoluminescence (PZL) in varying forms of material phases Ð fibers, flexible sheets, and bulk. PZL implies the generation of light of desired wavelength by mechanical action. The effect has been observed in compounds with suitable crystallographic symmetry when modified with activator ions. The underlying basis for the effect has been correlated with the presence of local piezoelectricity and energy states below the conduction band available from the suitable activator ion. However, to achieve extraordinary improvements in PZL response, a fundamentally new research direction is required. One promising possibility is to exploit Òdefect engineeringÓ in order to generate the trap states that facilitate the electron transfer. The concentration of trapped electrons is predicted to have a strong correlation with the PZL performance, and an optimum electron concentration is necessary to maximize PZL intensity due to adequate electron energy transfer ratio between non-radiative recombination (NRR) and thermal radiative recombination (TRR). Theoretical analysis, finite element models, and extensive experiments will focus on understanding the effect of various processing parameters that affect the evolution of nanoscale networked structures and the relationships between the component architecture and mechanical strain / band structure / optical properties. Microstructural engineering will be utilized to find geometrical arrangements / distributions that achieve elastic compatibility in the networked structure, which in turn will provide the opportunity to develop mathematical models that can predict the behavior of conceptual light emitting architectures. PZL can be utilized in various scenarios where mechanical energy is continuously available such as surfaces of aircrafts, automobiles and ships; roadways and pedestrian walkways; high deformation structures such as windmills and flexible rooftops; etc. New sensing technologies for stress, impact, and damage could be designed based on the PZL effect. The effect could also be used for visualization of stress propagation in structures such as pipes and mounts. Recently, a safety management system was proposed where a PZL-sensor emits light in response to mechanical stress which is detected by the image-sensing nodes that wirelessly communicate with the centralized system. The non-contact part of this system, wherein light is used for detection and communication, is highly attractive. Further, the stress sensing is passive as the PZL sensor responds directly by emitting light in response to the mechanical stimulation. The DOD Policy Memo on Fundamental Research dated May 24, 2010, provides guidance to ensure that DoD personnel will not restrict disclosure of the results of fundamental research. The Pennsylvania State University considers the scope of the proposed research to be fundamental research and anticipates there will be no publication approval or other requirements in the award that would restrict disclosure of the research results. There is no environmental impact of the proposed research. No Class I orClass II ozone-depleting substances will be used in this research.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Feb 14, 2019
- Source ID
- W911NF1810013
Entities
People
- Shashank Priya
Organizations
- Army Contracting Command
- Pennsylvania State University
- United States Army