Excitation‐Independent Emission of Carbon Quantum Dot Solids
Mai Xuân Dũng, Yen Thi Hai Phan, Van-Quang Nguyen
Abstract
Solid assemblies of carbon quantum dots (CQDs) are important for diverse applications including LEDs, solar cells, and photosensors; their optical and electrical properties have not been explored yet. Herein, we used amphiphilic CQDs synthesized from citric acid and thiourea by a solvothermal method to fabricate CQD solid films. Optical properties of CQDs studied by UV‐Vis and photoluminescence spectroscopies indicate that CQDs possess three different emission centers at 425 nm, 525 nm, and 625 nm originating from C sp 2 states, N‐states, and S‐states, respectively. In a solid state, π ‐ π stacking quenched the blue emission, while the red emission increased. Importantly, CQD films exhibited excitation independence, which is important to design solid‐state lighting applications.