CdTe_0.25Se_0.75 Quantum Dots Showed Efficient Room-Temperature Single Photon Emission

Room-temperature single photon sources (SPS) are crucial for developing next-generation quantum technologies. Quantum dots (QDs) have recently been reported as promising materials for SPS at room temperature. Our study highlights a new mechanism to enhance single photon emission through trap state-assisted enhancement in single photon emission purity by optimizing the single particle optical properties of a series of water-soluble CdTe_xSe_1-x QDs. We achieved an efficient SPS in CdTe_0.25Se_0.75 QDs with a second-order photon correlation value (g²(0)) as low as 0.02. They also exhibited deterministic emissions, with some QDs exhibiting ON time exceeding 95% of the total time. This was accompanied by an increased photon count rate, substantially reduced blinking events, and extended single particle ON-time. The increased single photon emission with enhanced ON time is attributed to simultaneous electron and hole trapping to dense trap states, which encourages the single photon emission for a long time.