I recently found an online play-through of a game called OneShot, a fourth wall breaking game in which the main character, Niko, has to restore the sun (just a giant lightbulb) to a world in which the previous sun died out with the help of the player, who acts as a... far from omniscient god of the world that can't directly interact with anything and can only be heard by Niko. Throughout the game, characters reference a material called phosphor, which they say gives off the power of their previous sun, and is used to provide light, generate power, and grow plants.
While bored, I decided to do a quick google search for phosphor, and it turns out it's actually a real thing, although it doesn't function as it does in the game. In real life, phosphor is a luminescent material used to coat various lights in order to change the color that they emit, with the simplest example being LEDs. For example, most white LED lights actually utilize a blue light to generate their light. How does the light become white then? The answer is that there's a phosphor coating around the light which absorbs light at the blue wavelength, and re-emits light at longer wavelengths, resulting in a full spectrum of visible light instead of a single color. And it should be noted that phosphor isn't a single compound, however, but an entire category of compounds. By changing which compound is used, as well as its density, its possible to achieve a variety of affects from simple lighting to creation of glow-in-the dark materials.