A spinel-type sulfide semiconductor that can emit light from violet to orange at room temperature has been developed by researchers at Science Tokyo, overcoming the efficiency limitations of current LED and solar cell materials. The material, (Zn, Mg)Sc2S4, can be chemically tuned to switch between n-type and p-type conduction, leading to future pn homojunction devices. This versatile semiconductor offers a practical path toward the development of more efficient LEDs and solar cells.