The deep blue of your LED display is likely produced by indium gallium nitride (InGaN), a costly substance. In the field of LEDs, researchers are seeking alternatives in a type of perovskite known as quasi-2D Ruddlesden‒Popper perovskites (2D-RPPs). 2D-RPPs have excellent optoelectronic properties—ideal for LEDs. Although 2D-RPP-based LEDs have rapidly progressed in terms of performance, it is still challenging to demonstrate blue-emissive and color-pure LEDs.