Adam Marcus, Erdem Talha, Stachowski Gordon M, Soran-Erdem Zeliha, Lox Josephine F L, Bauer Christoph, Poppe Jan, Demir Hilmi Volkan, Gaponik Nikolai, Eychmüller Alexander
Physical Chemistry, TU Dresden , Bergstr. 66b, 01062 Dresden, Germany.
Department of Electrical and Electronics Engineering, Department of Physics, and UNAM-Institute of Materials Science and Nanotechnology, Bilkent University , TR-06800 Ankara, Turkey.
ACS Appl Mater Interfaces. 2015 Oct 21;7(41):23364-71. doi: 10.1021/acsami.5b08377. Epub 2015 Oct 12.
In this work, a model-experimental feedback approach is developed and applied to fabricate high-quality, warm-white light-emitting diodes based on quantum dots (QDs) as color-conversion materials. Owing to their unique chemical and physical properties, QDs offer huge potential for lighting applications. Nevertheless, both emission stability and processability of the QDs are limited upon usage from solution. Incorporating them into a solid ionic matrix overcomes both of these drawbacks, while preserving the initial optical properties. Here borax (Na2B4O7·10H2O) is used as a host matrix because of its lower solubility and thereby reduced ionic strength in water in comparison with NaCl. This guarantees the stability of high-quality CdSe/ZnS QDs in the aqueous phase during crystallization and results in a 3.4 times higher loading amount of QDs within the borax crystals compared to NaCl. All steps from the synthesis via mixed crystal preparation to the warm-white LED preparation are verified by applying the model-experimental feedback, in which experimental data and numerical results provide feedback to each other recursively. These measures are taken to ensure a high luminous efficacy of optical radiation (LER) and a high color rendering index (CRI) of the final device as well as a correlated color temperature (CCT) comparable to an incandescent bulb. By doing so, a warm-white LED with a LER of 341 lm/Wopt, a CCT of 2720 K and a CRI of 91.1 is produced. Finally, we show that the emission stability of the QDs within the borax crystals on LEDs driven at high currents is significantly improved. These findings indicate that the proposed warm-white light-emitting diodes based on QDs-in-borax hold great promise for quality lighting.
在这项工作中，开发了一种模型-实验反馈方法，并将其应用于制造基于量子点（QDs）作为颜色转换材料的高质量暖白色发光二极管。由于其独特的化学和物理性质，量子点在照明应用中具有巨大潜力。然而，从溶液中使用时，量子点的发射稳定性和可加工性都受到限制。将它们掺入固体离子基质中克服了这两个缺点，同时保留了初始光学性质。在此，硼砂（Na2B4O7·10H2O）被用作主体基质，因为与氯化钠相比，它在水中的溶解度较低，从而降低了离子强度。这保证了高质量的CdSe/ZnS量子点在结晶过程中在水相中的稳定性，并且与氯化钠相比，硼砂晶体中量子点的负载量高出3.4倍。从合成到混合晶体制备再到暖白色发光二极管制备的所有步骤都通过应用模型-实验反馈进行了验证，其中实验数据和数值结果相互递归提供反馈。采取这些措施是为了确保最终器件具有高发光效能（LER）、高显色指数（CRI）以及与白炽灯泡相当的相关色温（CCT）。通过这样做，制造出了一种LER为341 lm/Wopt、CCT为2720 K且CRI为91.1的暖白色发光二极管。最后，我们表明，在高电流驱动的发光二极管上硼砂晶体中的量子点的发射稳定性得到了显著提高。这些发现表明，所提出的基于硼砂中量子点的暖白色发光二极管在高质量照明方面具有巨大潜力。
