Thick-Shell Colloidal Quantum Dots (original) (raw)

While over the last years the syntheses of colloidal quantum dots (CQDs) with core/shell structures were continuously improved to obtain highly efficient emission, it has remained a challenge to use them as active materials in laser devices. Here, we report on a successful demonstration of random lasing at room temperature in films of CdSe/CdS CQDs with different core/shell band alignments and extra thick shells. Even though the lasing process is based on random scattering, we find systematic dependencies of the laser thresholds on film morphology and excitation spot size. This systematics suggests that random lasing experiments are a valuable tool for testing nanocrystal materials, providing a direct and simple feedback for the further development of colloidal gain materials towards lasing in continuous wave operation.