Multi-quantum-well quantum dots with stable dual emission†
Multi-quantum-well quantum dots (MQW-QDs) with multiple emission peaks have been evaluated as promising single source emitters in the fabrication of high performance white LEDs. However, they still face a critical issue of color shift in practical applications, which is mainly attributed to the redistribution of the excitons between the adjacent wells under different excitation powers. Herein, we report sandwich structural MQW-QDs that provide highly stable dual emission. The study on the optical properties and exciton dynamics reveals that the thickness of the inner-barrier plays a crucial role in balancing the exciton distribution through regulating near-field energy transfer and light absorption between the adjacent wells. Meanwhile, the wells and the outer-barrier mainly influence the luminescence efficiency and the wavelength control of the dual emission peaks. The MQW-QDs with a minimum color shift versus excitation power are finally achieved by optimizing the structure parameters. A white LED based on the developed MQW-QDs exhibits a stable white light spectrum with high tolerance to the change of the excitation power, ensuring the advancement of the performance of MQW-QDs in lighting and display applications.