CAREER: Realizing next generation light-material interactions via directional, collective photoluminescence and energy transport of surface-sensitive nanocrystals

非技术性描述电子设备无处不在，并推动能源需求不断增长。节能设备将通过可再生能源发电和减少能源消耗在满足这些需求方面发挥重要作用。能源效率的一个例子来自广泛用于显示器和照明的发光二极管（LED）。向前方向发射的光逸出设备并被看到。以广角发射的光可能被困在设备内部并被浪费。因此，控制光发射的方向可以增加LED的效率。这个职业项目的重点是了解纳米材料的基本电子和光子过程，可以表现出高度定向的光发射。这项工作的发现可以实现超高效率的照明，显示器和太阳能电池。它们还将为光学计算和数据存储等新技术提供基础。调查员还将通过培训妇女和代表性不足的少数民族成为STEM的领导者来解决可持续性方面的技术和社会挑战。计划的活动包括案例研究项目，本科生研究机会，以及以太阳能行业为重点的技术学院。技术描述这个CAREER项目的目标是了解铯铅卤化物纳米晶体的物理学，铯铅卤化物纳米晶体是一种高性能的纳米材料，具有非凡的光学特性，如超荧光，单光子发射，能量和自旋泛函。三个研究目标是通过研究角寿命将这些纳米晶体的可调谐的定向光致发光与超荧光相关联;确定这些材料中激子和自旋方向性的极限;并量化表面电荷和施加电压对单个纳米晶体的激子传输和发光途径的影响。研究小组将使用一系列光学表征技术来量化光和能量传输如何取决于单个纳米晶体和超晶格的大小、形状、成分和局部环境。由于非凡的光学特性表现出强烈的角度依赖性，研究团队将使用时间分辨后焦平面成像来量化作为角度和动量函数的光发射和能量转移的时间特性。这项工作是在材料合成的化学方法和表面化学以及光子设计原理的交叉点上进行的，这些原理决定了材料中的光传播，创造了一个理解纳米级光-物质相互作用所必需的视角。这项工作将揭示其他纳米材料系统，并有可能使新的量子信息技术和光电技术的效率接近热力学极限。该奖项反映了NSF的法定使命，并已被认为值得通过使用基金会的智力价值和更广泛的影响审查标准进行评估的支持。

Nontechnical DescriptionElectronic devices are everywhere, and drive increasing demands for energy. Energy-efficient devices will play an important role in addressing these needs through renewable energy generation and reduced energy consumption. One example of energy efficiency comes from light-emitting diodes (LEDs), widely used for displays and lighting. Light emitted in the forward direction escapes the device and is seen. Light emitted at a wide angle can be trapped inside the device and is wasted. Thus, controlling the direction of light emission can increase the efficiency of an LED. This CAREER project focuses on understanding the fundamental electronic and photonic processes of nanoscale materials that can exhibit highly directional light emission. Discoveries in this work could enable ultra-high efficiency lighting, displays, and solar cells. They also will provide the foundation for novel technologies such as optical computing and data storage. The investigator will also address the technological and social challenges in sustainability by training women and underrepresented minorities to be leaders in STEM. Planned activities include case study projects, undergraduate research opportunities, and a solar industry-focused Technical Academy. Technical DescriptionThe goal of this CAREER project is to understand the photophysics of cesium lead halide nanocrystals, a high-performance nanomaterial with extraordinary optical properties such as superfluorescence, single photon emission, and energy and spin funneling. The three research objectives are to correlate the tunable, directional photoluminescence to superfluorescence of these nanocrystals by studying angular lifetime; determine the limit of exciton and spin directionality in these materials; and quantify the effect of surface charge and applied voltage to the exciton transport and light emission pathways of individual nanocrystals. The research team will quantify how light and energy transport depends on the size, shape, composition, and local environment of individual nanocrystals and superlattices using an array of optical characterization techniques. Because extraordinary optical properties exhibit strong angle dependence, the research team will use time-resolved back focal plane imaging to quantify the temporal properties of light emission and energy transfer as a function of angle and momentum. The work operates at the intersection of chemical approaches to materials synthesis and surface chemistry and photonic design principles that dictate light propagation in materials, creating a perspective that will be necessary to understanding nanoscale light-matter interactions. This work will shed light on other nanomaterial systems and has the potential to enable novel quantum information technologies and optoelectronic technologies with efficiencies approaching thermodynamic limits.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.