Xia Puzhen, Xie Bin, Luo Xiaobing
School of Energy and Power Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Micromachines (Basel). 2022 Jul 30;13(8):1222. doi: 10.3390/mi13081222.
The photoluminescent composite, which consists of micro-/nanoscale photoluminescent particles and a polymer matrix, plays a key role in optical wavelength conversion in white-light-emitting diodes (WLEDs). Heat is inevitably generated within the composite due to the energy lost through conversion and cannot be easily dissipated due to the extremely low thermal conductivity of the polymer matrix. Consequently, the composite suffers from a high working temperature, which severely deteriorates its optical performance as well as its long-term stability in WLEDs. To tackle this thermal issue, in this work three-dimensional (3D)-interconnected thermal conducting pathways composed of hexagonal boron nitride (hBN) platelets were constructed inside a photoluminescent composite, using a simplified bubbles-templating method. The thermal conductivity of the composite was efficiently enhanced from 0.158 to 0.318 W/(m∙K) under an ultralow hBN loading condition of 2.67 wt%. As a result, the working temperature of the photoluminescent composite in WLEDs was significantly reduced by 32.9 °C (from 102.3 °C to 69.4 °C, under 500 mA). Therefore, the proposed strategy can improve the heat accumulation issue in photoluminescent composites and thus improve the optical stability of WLEDs.
由微/纳米级光致发光颗粒和聚合物基体组成的光致发光复合材料，在白光发光二极管（WLED）的光波长转换中起着关键作用。由于转换过程中能量损失，复合材料内部不可避免地会产生热量，且由于聚合物基体的热导率极低，热量难以轻易消散。因此，该复合材料工作温度较高，这严重恶化了其在WLED中的光学性能以及长期稳定性。为了解决这一热问题，在本工作中，采用简化的气泡模板法，在光致发光复合材料内部构建了由六方氮化硼（hBN）片晶组成的三维（3D）互连导热通道。在2.67 wt%的超低hBN负载条件下，复合材料的热导率从0.158有效提高到0.318 W/(m∙K)。结果，WLED中光致发光复合材料的工作温度显著降低了32.9 °C（在500 mA下，从102.3 °C降至69.4 °C）。因此，所提出的策略可以改善光致发光复合材料中的热积累问题，从而提高WLED的光学稳定性。
