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Design Rules for Obtaining White Light from Layered Perovskites and Related Lattices

从层状钙钛矿和相关晶格获得白光的设计规则

基本信息

批准号：
1904443
负责人：
Hemamala Karunadasa
金额：
$ 50万
依托单位：
Stanford University
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2019
资助国家：
美国
起止时间：
2019-08-15 至 2023-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1904443&HistoricalAwards=false
关键词：
Design Rules Obtaining White Light

项目摘要

PART 1: NON-TECHNICAL SUMMARYThe transition to solid-state lighting (SSL) is predicted to halve global electricity consumption for lighting by the year 2025. SSL devices use light-emitting diodes (LEDs) coated with a phosphor material, which converts blue or ultraviolet light from the LED to white light. The emitted light must span the entire visible spectrum, similar to sunlight, in order for the lighting to accurately show the colors of illuminated objects. However, phosphors with such broadband emission are very rare. Commercial SSL devices mix LEDs and phosphors of different colors to achieve broadband white light, but a single material that emits broadband white light is highly desirable for artificial illumination. Layered hybrid perovskites are crystalline materials that contain alternating organic and inorganic layers. The inorganic layers of some layered metal-halide perovskites can convert ultraviolet light to broadband white light. The proposed work, supported by the Solid State and Materials Chemistry and Electronic and Photonic Materials programs in the Division of Materials Research, seeks to expand white-light emission to a much larger range of lattices. Nontoxic compositions, in particular, will be targeted. To date, the discovery of new white-light-emitting metal halides remains serendipitous. This research will identify and disseminate design rules for the predictable synthesis of white-light emitters. Undergraduate researchers will be involved in all aspects of the research. A new course will introduce general chemistry concepts to first-year students using examples from materials chemistry. Concepts in solid state and inorganic chemistry, which are typically not included in first-year courses, will be introduced in general chemistry in order to draw students to these fields early. Outreach activities at local high schools and at Stanford University will also emphasize the importance of materials discovery, with demonstrations including new materials synthesized in the PI's group. PART 2: TECHNICAL SUMMARYBroadband white-light emission from a single material without discrete chromophores is extremely unusual. Such an emission has been reported from the inorganic layers of 2D hybrid halide perovskites, attributed to exciton self-trapping. Although a growing number of metal-halide broadband emitters are now being reported, they remain as relatively rare, isolated examples driven by serendipitous discovery. This research, supported by the Solid State and Materials Chemistry and Electronic and Photonic Materials programs in the Division of Materials Research, seeks to probe the generality of exciton self-trapping in a large range of lattices to substantially increase the number of intrinsic white-light emitters. Synthetic and optical studies of 0D, 1D, and 2D lattices with varying composition and connectivity will allow for the articulation of overarching design rules for the rational synthesis of white-light emitters. Steady-state and time-resolved spectroscopies will probe correlations between the ground-state structure of the lattices and excited-state distortions associated with self-trapping. These methods will also interrogate the role of extrinsic self-trapping by studying the influence of native and chemically induced lattice defects on the emission. The fundamental studies outlined here are expected to set the stage for the synthesis of materials that can manipulate light in a predictable manner. Single-source white-light emitters eliminate problems associated with current methods of producing white light by mixing multiple different phosphors or light-emitting diodes. The fundamentally different emission mechanism in these hybrids compared to those of inorganic phosphors and organic LEDS may open new niches for their use in large-area displays and panels. Undergraduate researchers will be involved in all aspects of the research. New materials synthesized for this project will be included in high school outreach events. A new course will introduce general chemistry concepts to first-year students using examples from materials chemistry. Concepts in solid state and inorganic chemistry, which are typically not included in first-year courses, will be introduced in general chemistry in order to draw students to these fields early.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.

第一部分：预计到2025年，向固态照明（SSL）的过渡将使全球照明用电量减半。SSL器件使用涂覆有磷光体材料的发光二极管（LED），其将来自LED的蓝光或紫外光转换为白色光。发射的光必须跨越整个可见光谱，类似于阳光，以便照明准确地显示被照明物体的颜色。然而，具有这种宽带发射的磷光体非常罕见。商业SSL装置混合不同颜色的LED和磷光体以实现宽带白色光，但是发射宽带白色光的单一材料对于人工照明是高度期望的。层状混合钙钛矿是含有交替的有机层和无机层的结晶材料。一些层状金属卤化物钙钛矿的无机层可以将紫外光转换为宽带白色光。这项由材料研究部的固态和材料化学以及电子和光子材料计划支持的拟议工作旨在将白光发射扩展到更大范围的晶格。具体地，将靶向无毒组合物。迄今为止，新的发白光的金属卤化物的发现仍然是偶然的。这项研究将确定和传播可预测的合成白光发射器的设计规则。本科研究人员将参与研究的各个方面。一门新课程将使用材料化学的例子向一年级学生介绍一般化学概念。固态和无机化学的概念，通常不包括在第一年的课程，将在普通化学介绍，以吸引学生到这些领域的早期。当地高中和斯坦福大学的外展活动也将强调材料发现的重要性，演示包括PI小组合成的新材料。第二部分：技术概述没有离散发色团的单一材料的宽带白光发射是极不寻常的。已经报道了来自2D混合卤化物钙钛矿的无机层的这种发射，归因于激子自捕获。虽然越来越多的金属卤化物宽带发射器现在被报道，他们仍然是相对罕见的，孤立的例子驱动的偶然发现。这项研究由材料研究部的固态和材料化学以及电子和光子材料项目支持，旨在探索大范围晶格中激子自陷的一般性，以大幅增加固有白光发射器的数量。具有不同组成和连接性的0D，1D和2D晶格的合成和光学研究将允许用于白光发射器的合理合成的总体设计规则的接合。稳态和时间分辨光谱将探测晶格的基态结构和与自陷相关的激发态畸变之间的相关性。这些方法还将通过研究本机和化学诱导的晶格缺陷对发射的影响来询问非本征自陷的作用。这里概述的基础研究有望为合成能够以可预测的方式操纵光的材料奠定基础。单源白光发射器消除了与通过混合多种不同的磷光体或发光二极管产生白色光的当前方法相关联的问题。与无机磷光体和有机LED相比，这些混合物中根本不同的发射机制可能为其在大面积显示器和面板中的使用开辟新的利基市场。本科研究人员将参与研究的各个方面。为该项目编写的新材料将纳入高中外联活动。一门新课程将使用材料化学的例子向一年级学生介绍一般化学概念。固体化学和无机化学的概念通常不包括在第一年的课程中，将在普通化学中引入，以吸引学生尽早进入这些领域。该奖项反映了NSF的法定使命，并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，被认为值得支持。