Smart Materials for Zero Additional Energy: Europium- and Dysprosium-Doped Strontium Aluminate for Low-Level Artificial Light at Night

The integration of information technology in the built environment is intended to enable the efficient use of energy without compromising the comfort of humans. However, these devices and systems require a constant supply of energy, adding to the already high demand. In an attempt to promote zero additional energy-demand practices, this study explores the application of the direct and reversible property of smart photoluminescent material in the generation of artificial light at night (ALAN), where low-level light (LLL) is required for the identification of hazards. To achieve this, the energy transformation capacity of europium- and dysprosium-doped strontium aluminate (SrAl2O4:Eu2+, Dy3+) in the generation of visible light via photoluminescence was investigated. The performance of the material as a photoluminescent (PL) tape and component in PL paint was documented after activation by sunlight, inspired by evaluation tests and the Standard Test Method for Photopic Luminance of Photoluminescent Markings. From the single preliminary observation, tape luminance from initial tests in August 2020 declined from derived 8550 mcd/m2 to 3150 mcd/m2 at 10 min and 60 min respectively; then in September 2021, from derived 11,700 mcd/m2 to 4500 mcd/m2 at 10 min and 60 min respectively, after an additional tape layer was applied in a separate campaign. The 10- and 60 min checkpoints evaluate how well the tape holds its brightness over time. For the paint, symbol recognition remained visible up to 90 min and became indistinct after 120–150 min after activation, supporting qualitative symbol discernibility under the stated test conditions. The coating dried hard in 25 min, set to touch in 12 h, and retained afterglow after 24 h water immersion and exposure to 0 °C and 42 °C. These exploratory, non-replicated results demonstrate persistent afterglow and qualitative symbol discernibility under the stated laboratory conditions and support further controlled evaluation for low-light built-environment applications.