Ultrastable and Low‐Threshold Random Lasing from Narrow‐Bandwidth‐Emission Triangular Carbon Quantum Dots

Abstract The development of ultrastable and low‐threshold random lasers has long been the subject of intense academic research, in anticipation for widespread applications spanning from military weapon devices, biomedical therapy, and materials processing to energy savings. Reported here is the first example of ultrastable and low‐threshold random lasing emissions ranging from blue to red based on narrow bandwidth emission triangular carbon quantum dots (CQDs). The lasing thresholds of the blue, green, and red random lasers are determined to be as low as 0.087, 0.052, and 0.048 mJ cm −2 , and the corresponding narrow full widths at half maximum are 0.9, 0.37, and 0.82 nm, respectively. Furthermore, such random lasers demonstrate outstanding stability. This work will inspire further research on lasers operating in other modes, based on the CQDs, such as the whispering‐gallery mode and the Fabry–Pérot mode, which will expedite the development of the next‐generation of ultrastable and low‐threshold CQDs‐based laser technology.