The correlated color temperature (CCT) of lighting is closely related to human emotions. However, there is still a relative lack of white light emitting devices (W-LEDs) with tunable CCT to meet application demands in different scenarios. Here, we develop a W-LED with tunable CCT based on multiple emissive centers of carbon dots (CDots) synthesized through controlled thermal carbonization of citric acid and urea. The reaction at 160 °C for 4 h results in amorphous CDots, which exhibit excitation wavelength dependent photoluminescence (PL) containing two peaks at 446 and 520 nm. However, by increasing the reaction temperature and duration, crystalline CDots are obtained, which show broad PL peaking at 650 nm. Based on their complementary spectral ranges, a W-LED with an extremely high color rendering index of 96 is demonstrated. Moreover, a W-LED with both 365 and 405 nm electroluminescent chips is designed. The W-LED shifts from cold to warm white, when the excitation chips switch from 365 to 405 nm. This adjustable CCT can create a harmonious, enjoyable, and safe lighting environment to meet the demands of different scenes.

中文翻译：

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基于多发射中心碳点的可调谐冷/暖白光发光器件


照明的相关色温（CCT）与人类的情绪密切相关。然而，目前仍相对缺乏具有可调色温的白光发光器件（W-LED）来满足不同场景的应用需求。在这里，我们开发了一种具有可调谐 CCT 的 W-LED，其基于通过柠檬酸和尿素的受控热碳化合成的碳点 (CDots) 的多个发射中心。在 160 °C 下反应 4 小时会产生非晶态 CDot，其表现出激发波长依赖性光致发光 (PL)，包含 446 和 520 nm 处的两个峰。然而，通过增加反应温度和持续时间，可以获得结晶 CDot，其在 650 nm 处显示出宽的 PL 峰值。基于其互补的光谱范围，展示了具有 96 极高显色指数的 W-LED。此外，还设计了具有365和405 nm电致发光芯片的W-LED。当激发芯片从 365 nm 切换到 405 nm 时，W-LED 就会从冷白色转变为暖白色。可调色温可以营造和谐、愉悦、安全的照明环境，满足不同场景的需求。