用于可见光光谱重建的窄谱LED发光机理研究

Colour reproduction of light sources or image pixel through spectral recovery is a forward looking topic and the research has great significance. Although the entire wavelength of visible light can be covered by current LEDs, spectrum shape of single LED is not as narrow as expected to achieve the gamut realization or simulation. This research aims to study the restriction of radiative mechanism of LEDs by analyzing the elements (such as: internal band structure, crystalline quality, composition variation and injection level etc.) that could influence the spectrum broaden effect. In addition, the project will look into the theoretical limit of the factors mentioned above. Meanwhile, the research will present spectrum narrowing/restriction proposal through application of optical limits via filters and/or internal photon recycling. In other words, output spectrum of a LED is narrowed/restricted by using optical elements with narrow band while the reflected photons will be absorbed at the active region and re-emitted to avoid substantial radiative efficiency decrease.

通过光谱再现的方式实现光源或者图像像素的真实再现是有着重要价值和前瞻性的科研内容。现有发光二极管产品（Light-Emitting Diode, LED）的发光光谱已经能够覆盖全部可见光波段，但是单个LED的光谱形状与期待中全光谱拟真的要求仍有差距。本项目拟对限制LED的发光机理进行研究，分析其内部能带结构、晶体质量、组分波动、注入电流密度等影响光谱展宽的因素，在对现有LED器件中常用的光学限制方法进行分析的基础上，提出利用存在波长选择机制的片上光学限制使得LED发射光谱窄化的方法，该方法拟利用窄通带光学元件作为LED芯片结构的出光窗口，通过光学限制方式使得LED的发光光谱形态得以控制，同时对器件内部光子循环效应机理进行研究以指导器件结构，试图在获得窄带发射的同时避免器件发光效率的大幅下降。

项目主要进行了如下工作：.1、对限制LED光谱特性的发光机理进行了研究，分析了LED能带结构、晶体质量、组分波动、注入电流密度等影响光谱展宽的因素，对片上光谱反馈机制的区别进行了理论分析，针对薄膜LED的反射层进行了专门设计，对现有LED器件中常用的光学限制方法进行了分析，提出了实验方案。通过窄带滤光薄膜的方法将现有蓝光LED器件的光谱谱线宽度降低到15nm以下。.2、项目分析了LED全光谱拟和的需求，对现有LED光源光谱和LED全光谱拟真工作进行了进一步分析，开展了相关实验研究。利用现有设备，结合工艺搭建了一套多光谱LED封装工艺和测试平台，利用该平台进行了多光谱稳定性研究，主要实验波长覆盖了可见光区的主要波段，实现了对单个波长的分级控制，计算和测量了光谱形状控制对主要人视觉参数的影响。.项目已发表文章1篇，正在修订1篇。