Speckle-free laser display enabled by self-assembled supraparticles of semiconductor nanoplatelets

Laser-based light sources are highly desirable for display applications due to their narrow emission linewidth and exceptional brightness. However, the coherence inherent in lasers often leads to the formation of unwanted speckles, which can significantly degrade display quality. Thus, there is a critical need for light sources that retain the narrow emission and high brightness of lasers while minimizing spatial coherence to reduce speckle formation. Random lasing has emerged as a promising strategy to address this issue, though its random emission directions can lead to energy losses. To overcome this challenge, we propose a novel approach in which CdSe nanoplatelets, known for their efficient optical gain properties, are self-assembled into supraparticles (SPs), serving as both scattering centers and gain media. This configuration enables random lasing, and by coupling the random gain medium to a Fabry–Pérot (FP) cavity, we successfully direct the typically omnidirectional random lasing into a controlled, low-coherence emission. Our experimental results, comparing conventional lasers (e.g., He:Ne lasers) with our SP-based laser for a projector, demonstrate effective suppression of speckle formation, reducing speckle contrast from 0.5 to 0.05. These findings offer a promising solution for improving the performance and quality of laser-based displays.