Credit: Letian Dou/Berkeley Lab and Connor G. Bischak/UC Berkeley
Single nanowires shown emitting different colors. The top panel shows a cesium lead bromide (CsPbBr3)-cesium lead chloride (CsPbCl3) heterojunction simultaneously emitting green and blue lights, respectively, under UV excitation. The bottom panel shows a cesium lead iodide (CsPbI3)-cesium lead bromide-cesium lead chloride configuration emitting red, green, and blue lights, respectively.