Philippine E-Journals

PHOTOLUMINESCENT STRUCTURES: A TRUE EXPERIMENTAL STUDY INTO LUMINOUS FLUX EFFICIENCY AND VIABILITY

Julian Harish Bhojwani | Kenneth Obillos | Carmela Joy Manalastas | Anne Marie Parcon | John Gonzales | Austin Marcelo | Christian Rodavites | Jatz Cudo | Monique Molina | John Romy Delfin | Eric N. Awi

 

Abstract:

Photoluminescence structure is a concept that has existed for decades. The idea that a single structure could emit natural light without the need for electricity, dangerous emittance of temperature or radiation has enticed engineers. The phosphor ZnS:Ag or Silver- Activated Zinc Sulfide is known for its brilliant blue hue during photoexcitation. This generates a bright and sustained emission of light without the need of electricity. As the reaction is not caused by direct heat or a reaction due to ignition or explosion, it is not considered phosphorescent in nature. But rather photoluminescent. This is mainly because the process, photoexcitation, causes light photons to be absorbed by the molecular structure of the atoms. Known to be stable and highly efficient as a semiconductor, the light emitted by the reaction is bright blue as silver is its activator. In order to determine the efficiency, luminous flux (lx), a derived unit of measurement from lumens (lm), in which it too is derived from the base SI Unit- Candela (cd) is used. One lx is equivalent to one lm per square meter. Over time, the efficiency can be determined. Additionally testing for Viability (V) is determined by three sub-variables, namely V1-lm or Light observed on objects, V2-t, or luminescence endurance, and V3E-lm or Environmental luminescence. Combined they are used to determine the viability of the phosphor in physical applications as a replacement to traditional light sources such as CFL, LED, or Incandescent. The light is measured through photometry and not photo-spectroscopy. This involves the use of a photometer rather than a spectrometer. This is done because the test sample is not quartz-cubed and would require a laser-based spectrometer. To simplify and receive similar results with respect to the instrument, a photometer is used instead. The collected data is originally determined in Lux but is converted into the needed data. After following a stringent testing protocol, the data is tabulated, analyzed, and graphed. The data was found to show a trend in decreasing luminosity count in relation with time. As time increased, luminosity decreased. This is expected as the phosphor gradually loses its photons to emit, and thus light is slowly reduced to undetectable units. Additionally, the length of time it took for the luminosity of the phosphor to become undetectable was surprisingly high. Averaging seven to eight hours at maximum peak brightness of 3.9 lux.