柔性微型无机发光二极管的热管理

Thermal management for microscale inorganic light-emitting diodes

基于无机材料的发光二极管(Inorganic Light-Emitting Diodes,简称ILED)由于效率高、寿命长、响应快、方向性好等优点被广泛应用于各个领域,例如固态发光照明、光学通信和光遗传学等.与柔性衬底相结合制备得到的柔性ILED具备了能够任意弯折、扭转或拉伸这些传统LED所没有的特性,可以实现与大脑、皮肤、器官等柔软组织的集成,这为以后临床需要的医疗检测和诊断提供了可能性.本文针对矩形形状柔性ILED的传热过程建立理论和有限元仿真模型,解析得到LED中的温度场分布及其随着LED尺寸的变化规律,所得的理论预测与有限元仿真结果吻合地较好.通过理论模型,建立了ILED无量纲温升的比例定律,并研究了柔性LED正常发光工作时的无量纲温升随无量纲几何和无量纲材料参数的变化规律,这些结果为矩形柔性LED的热管理提供了理论依据,对柔性LED的设计具有一定的指导意义.

Inorganic Light-Emitting Diodes（ILEDs） are attractive for broad classes of applications in solid-state lighting, optical communication, and optogenetics due to their high efficiency, fast response, and long lifetime etc. The recently developed flexible ILED enables lots of novel applications especially in bio-integrated therapeutic devices that could be integrated with soft tissues well because they are able to be deformed like a rubber band. The low thermal conductivity of the elastomeric substrate in flexible ILEDs, which is about 3 orders of magnitude lower than that of the typical substrate for conventional ILEDs, imposes critical challenges in the thermal management. In this paper, an analytical model, validated by three dimensional finite element simulations, is developed to study the thermal properties of microscale inorganic LEDs with a rectangular shape. The temperature rise of ILED is derived analytically and agrees well with finite element simulations. A simple scaling law for the ILED temperature rise is then established in terms of the material and geometrical parameters. It is found that the ILED temperature rise depends on only 4 non-dimensional parameters. These results pave the basis for thermal management of flexible ILEDs and provide design guidelines for minimizing their adverse thermal effects on the performance as well as in applications.