Departments of Electrical and Electronics Engineering, Physics, and Chemistry, UNAM-National Nanotechnology Research Center, and Institute of Materials Science and Nanotechnology, Bilkent University , Ankara 06800, Turkey.
Luminous! Center of Excellence for Semiconductor Lighting and Displays, School of Electrical and Electronic Engineering, School of Physical and Mathematical Sciences, Nanyang Technological University , Singapore 639798, Singapore.
ACS Nano. 2016 May 24;10(5):5333-9. doi: 10.1021/acsnano.6b01473. Epub 2016 May 9.
Oligomer nanoparticles (OL NPs) have been considered unsuitable for solid-state lighting due to their low quantum yields and low temperature stability of their emission. Here, we address these problems by forming highly emissive and stable OL NPs solids to make them applicable in lighting. For this purpose, we incorporated OL NPs into sucrose matrix and then prepared their all-organic monoliths. We show that wrapping the OL NPs in sucrose significantly increases their quantum yield up to 44%, while the efficiency of their dispersion and direct solid-film remain only at ∼6%. We further showed ∼3-fold improved temperature stability of OL NP emission within these monoliths. Our experiments revealed that a physical passivation mechanism is responsible from these improvements. As a proof-of-concept demonstration, we successfully employed these high-stability, high-efficiency monoliths as color converters on a blue LED chip. Considering the improved optical features, low cost, and simplicity of the presented methodology, we believe that this study holds great promise for a ubiquitous use of organic OL NPs in lighting and possibly in other photonic applications.
低量子产率和发射温度稳定性差，使低聚物纳米粒子（OL NPs）在固态照明领域的应用受到限制。本工作通过形成高效稳定的 OL NPs 固体来解决这些问题，以实现其在照明中的应用。为此，我们将 OL NPs 包裹在蔗糖基质中，然后制备了它们的全有机单体。结果表明，蔗糖包裹 OL NPs 可将其量子产率显著提高至 44%，而其分散效率和直接固态薄膜的效率仍保持在约 6%。我们进一步表明，在这些单体中，OL NP 发射的温度稳定性提高了约 3 倍。实验表明，这些改进源于一种物理钝化机制。作为概念验证，我们成功地将这些具有高稳定性、高效率的单体用作蓝色 LED 芯片上的彩色转换器。考虑到所提出方法的光学性能改善、低成本和简单性，我们相信这项研究为在照明以及可能在其他光子应用中广泛使用有机 OL NPs 提供了巨大的前景。
