Triple Halide Ultrawide Bandgap Metal Halide Perovskites

非技术描述金属卤化物钙钛矿是溶液处理的半导体，具有吸引人的光学和电子特性，这使得能够制造高效和低成本的设备，如太阳能电池和发光二极管（LED）。迄今为止，用于最有效设备的钙钛矿吸收红光和近红外光。这对应于1.2至1.8电子伏特（eV）的带隙，其中eV是使电子移动通过1伏特的电势所需的能量的量。期望开发具有较高带隙的高质量材料以在太阳能电池中捕获更多的太阳能或从LED发射绿色或蓝色光。该团队假设，具有三种不同卤素原子的钙钛矿可以实现这些具有增加带隙的高质量材料。该团队将制造三卤化物钙钛矿，并彻底表征其结构，组成和性能。在这样做的过程中，该团队将扩大用于设备应用的可行钙钛矿的范围。这项工作将由科罗拉多博尔德大学和韦尔斯利学院合作完成。韦尔斯利学院是一所多元化的女子本科学院，大多数新生都是有色人种。韦尔斯利学院的本科生与主要学术机构和国家实验室的研究人员密切合作。这大大增加了他们的研究机会，并为学生提供接触研究生课程。该项目将有助于支持人口和扩大STEM的机会。技术描述该项目的目标是合成高性能的全无机钙钛矿半导体，带隙在1.9和2.1 eV之间。目前宽带隙钙钛矿的性能受到非辐射复合和环境不稳定性的限制。 假设三卤钙钛矿具有理想的性质，因为A位没有机会发生分层，氯将钝化缺陷，小的晶格参数将导致强键，并且不会有有机阳离子可以分解。该团队将研究一系列有前途的三卤化物钙钛矿，利用其专业知识来表征和理解混溶成分空间;绘制和理解这些材料中的不稳定性;并最终量化和优化选定三卤化物钙钛矿的光电性能。该团队将确定溶液化学如何影响钙钛矿成核，薄膜生长和性能以及由此产生的光电特性和稳定性。该团队将使用循环伏安法，原位光致发光和吸收光谱法以及X射线衍射来记录改进，以绘制缺陷密度和降解障碍。本计画的主要目的为：（1）优化新型三卤化物钙钛矿的合成;（2）量化宽禁带钙钛矿的稳定性与光电性能;以及（3）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评估，被认为是值得支持的。影响审查标准。

Non-technical DescriptionMetal halide perovskites are solution-processed semiconductors with attractive optical and electronic properties, which have enabled the fabrication of efficient and low-cost devices such as solar cells and light-emitting diodes (LEDs). Perovskites used in the most efficient devices to date absorb light in the red and near-infrared. This corresponds to a band gap of 1.2 to 1.8 electron volts (eV), with an eV being the amount of energy needed to move an electron across an electric potential of one volt. It is desirable to develop high quality materials with higher band gaps to capture more of the sun’s energy in a solar cell or emit green or blue light from an LED. The team hypothesizes that perovskites with three different halide atoms could realize these high-quality materials with increased band gaps. The team will fabricate triple-halide perovskites and thoroughly characterize their structure, composition and properties. In doing so the team will expand the range of viable perovskites for device applications. This work will be done collaboratively between the University of Colorado Boulder and Wellesley College. Wellesley College is a diverse women’s undergraduate college, where a majority of the incoming class identifies as people of color. Wellesley College undergraduates work closely with researchers at major academic institutions and national laboratories. This greatly increases their research opportunities and provides students with exposure to graduate programs. This project will serve to support that population and expand STEM opportunities.Technical DescriptionThe goal of this project is to synthesize high performance all-inorganic perovskite semiconductors with bandgaps between 1.9 and 2.1 eV. The performance of current wide bandgap perovskites is limited by non-radiative recombination and environmental instability. Triple halide perovskites are hypothesized to have desirable properties because there will be no opportunity for demixing to occur at the A-site, chlorine will passivate defects, the small lattice parameter will result in strong bonds and there will be no organic cation that could decompose. The team will investigate a range of promising triple halide perovskites, leveraging its expertise to characterize and understand the miscible composition space; map and understand the instabilities in these materials; and ultimately quantify and optimize the optoelectronic properties of select triple halide perovskites. The team will determine how solution chemistry impacts perovskite nucleation, film growth and performance and resultant optoelectronic properties and stability. The team will document improvements using cyclic voltammetry, in situ photoluminescence and absorption spectroscopy, and X-ray diffraction to map defect densities and barriers to degradation. This project is working towards (1) optimized synthesis of novel triple halide perovskites; (2) quantification of the stability of wide bandgap perovskites and optoelectronic performance; and (3) improved interfacial layers for surface passivation and carrier selection in wide bandgap perovskites.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.