Toward the energy optimization of smart lighting systems through the luminous potential of photoluminescence. (1st March 2023) - Chiatti, Chiara
Abstract: Lighting-related energy consumption has recently increased due to the significant expansion of buildings' floor area and the growing demand for lighting coming from the occupants. With the aim of mitigating the global warming phenomenon by reducing the impacts of fossil fuels-powered systems, the lighting sector has faced a continuous renovation through years, up to the modern and efficient light emitting diodes (LEDs) solutions. Moving from the basic principle of phosphor-converted LEDs, consisting in the combination of phosphor materials to the radiation emitted by a LED chip, the present research investigates the response of photoluminescent pigments with different absorption and emission spectra as a function of the specific spectral distribution of the excitation source. The evolution of photoluminescence is later investigated during both the charging and the decay phase. The performance of each "pigment–lamp" pair is characterized using a spectroradiometer and a specially designed experimental equipment. Results demonstrate how a yellow-emitting material is more suitable than others for lighting purposes, providing for the highest luminance values (up to 2.61 cd/m 2 ) and the longest decay time ( > 5 h). Moreover, the fastest activation of luminescence due to UV radiation (after 20–60 min of exposure) does not guarantee the most persistent and intense performance of the samples. Graphical abstract: Highlights: The coupling of photoluminescence and artificial light is studied for energy saving. Rare-earth pigments with various luminescent colors are exposed to multiple irradiating spectra. Photoluminescence evolution is monitored during both the charge and discharge phase. Different irradiations significantly change the re-emission of the same pigments. A yellow afterglow charged by blue or white light is the most suitable for lighting.