Ryckaert Jana, Correia António, Tessier Mickael D, Dupont Dorian, Hens Zeger, Hanselaer Peter, Meuret Youri
Opt Express. 2017 Nov 27;25(24):A1009-A1022. doi: 10.1364/OE.25.0A1009.
Quantum dots can be used in white LEDs for lighting applications to fill the spectral gaps in the combined emission spectrum of the blue pumping LED and a broad band phosphor, in order to improve the source color rendering properties. Because quantum dots are low scattering materials, their use can also reduce the amount of backscattered light which can increase the overall efficiency of the white LED. The absorption spectrum and narrow emission spectrum of quantum dots can be easily tuned by altering their synthesis parameters. Due to the re-absorption events between the different luminescent materials and the light interaction with the LED package, determining the optimal quantum dot properties is a highly non-trivial task. In this paper we propose a methodology to select the optimal quantum dot to be combined with a broad band phosphor in order to realize a white LED with optimal luminous efficacy and CRI. The methodology is based on accurate and efficient simulations using the extended adding-doubling approach that take into account all the optical interactions. The method is elaborated for the specific case of a hybrid, remote phosphor white LED with YAG:Ce phosphor in combination with InP/CdxZnSe type quantum dots. The absorption and emission spectrum of the quantum dots are generated in function of three synthesis parameters (core size, shell size and cadmium fraction) by a semi-empirical 'quantum dot model' to include the continuous tunability of these spectra. The sufficiently fast simulations allow to scan the full parameter space consisting of these synthesis parameters and luminescent material concentrations in terms of CRI and efficacy. A conclusive visualization of the final performance allows to make a well-considered trade-off between these performance parameters. For the hybrid white remote phosphor LED with YAG:Ce and InP/CdxZnSe quantum dots a CRI Ra = 90 (with R9>50) and an overall efficacy of 110 lm/W is found.
量子点可用于照明应用的白光发光二极管（LED）中，以填补蓝色泵浦LED和宽带荧光粉组合发射光谱中的光谱间隙，从而改善光源的显色特性。由于量子点是低散射材料，其使用还可以减少背散射光的量，这可以提高白光LED的整体效率。通过改变量子点的合成参数，可以轻松调整其吸收光谱和窄发射光谱。由于不同发光材料之间的再吸收事件以及光与LED封装的相互作用，确定最佳量子点特性是一项非常复杂的任务。在本文中，我们提出了一种方法，用于选择与宽带荧光粉组合的最佳量子点，以实现具有最佳发光效率和显色指数（CRI）的白光LED。该方法基于使用扩展倍增法进行的准确而高效的模拟，该方法考虑了所有光学相互作用。针对具有YAG:Ce荧光粉与InP/CdxZnSe型量子点组合的混合远程荧光粉白光LED的具体情况，对该方法进行了详细阐述。通过半经验的“量子点模型”，根据三个合成参数（核尺寸、壳尺寸和镉含量）生成量子点的吸收光谱和发射光谱，以包括这些光谱的连续可调性。足够快速的模拟允许在CRI和效率方面扫描由这些合成参数和发光材料浓度组成的完整参数空间。最终性能的确定性可视化允许在这些性能参数之间进行充分考虑的权衡。对于具有YAG:Ce和InP/CdxZnSe量子点的混合白色远程荧光粉LED，发现显色指数Ra = 90（R9>50），总效率为110 lm/W。
