Collaborative Research: Design and Discovery of Entropy-Stabilized Perovskite Halides for Optoelectronics

第一部分：非技术性的钙钛矿卤化物是一类激动人心的材料，可以通过低温合成方法制备，在光电子领域具有广阔的应用前景。该项目由材料研究部的固体和材料化学计划和已建立的刺激竞争研究计划(EPSCoR)共同资助，由缅因州大学和阿拉巴马大学的一个合作研究小组开发、合成和研究用于光电子学的新型钙钛矿型卤化物。在这项理论和实验相结合的研究中，该团队还评估了材料在环境条件下的稳定性。与传统的含有两到三种金属元素的卤化物不同，这些新开发的钙钛矿型卤化物由五种或五种以上的主要金属元素组成，浓度几乎相等。该工作计划的特点是理论和实验之间有一个封闭的反馈回路，并通过执行理论预测、开发合成方法、表征光电性能以及评估暴露在气体、光和热下的稳定性来关注材料的进展。从该项目中发现的新的钙钛矿型卤化物材料可能导致广泛的光电子应用，包括太阳能电池、发光器件、光电探测器和激光器、光电化学催化剂、辐射探测器和传感器。这项研究允许来自这两所大学跨学科项目的项目参与者在缅因州和阿拉巴马州进行互动，并为技术发展做出贡献。三名博士研究生和六名本科生接受了培训，以获得计算、实验和数据分析这三个基本支柱的技能和能力，这三个支柱是下一代劳动力的关键属性。向缅因州和阿拉巴马州的K-12学生、高中教师和普通公众传播STEM外联和教育活动的目的是传达合作能源材料设计驱动的研究如何与应对社会挑战相关。第二部分：技术总结这个项目由材料研究部固体和材料化学计划和已建立的促进竞争研究计划(EPSCoR)共同资助，旨在通过计算设计和实验实现一种新型的无铅钙钛矿型卤化物材料，具有增强的热力学和环境稳定性以及所需的光电性能。为了提高钙钛矿型卤化物的光电性能和稳定的环境性能，人们研究了含有五种或五种以上主要金属元素的稳定的钙钛矿型卤化物。关键的假设是，混合的组态熵在稳定单相晶体ESPH结构中起主导作用。这一假说的验证不仅为设计更稳定的钙钛矿型卤化物材料提供了一条新的实验可控的途径，而且还产生了独特的组成-结构-性能关系，这在化学秩序盛行的情况下是不存在的。具体目标是(I)使用高通量第一性原理计算预测能够产生稳定ESPH的金属元素的组合，(Ii)使用固相溶液、水热和溶剂沉淀法合成预测的ESPH，(Iii)表征合成的ESPH的组成、结构和光电性质，以及(Iv)评估和分析实验合成的ESPH在各种实验室环境下的稳定性，包括湿度、氧化/还原气体和热。该项目的新ESPH将大幅扩展钙钛矿型卤化物的化学空间，提供更多能力来调整和定制感兴趣的材料属性(如晶格参数、带隙、光学吸收强度和导电性)，并为包括太阳能电池、发光设备、光电化学催化剂、光电探测器和激光器、辐射探测器和传感器在内的各种光电子应用提供高潜力。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

PART 1: NON-TECHNICAL SUMMARYPerovskite halides are an exciting family of materials that can be prepared by low-temperature synthesis methods and are promising for a wide variety of optoelectronic applications. With this project, which is jointly funded by the Solid State and Materials Chemistry program in the Division of Materials Research and the Established Program to Stimulate Competitive Research (EPSCoR), a collaborative research team from the University of Maine and the University of Alabama develops, synthesizes, and investigates a new class of perovskite halides for optoelectronics. In this combined theoretical and experimental investigation, the team also evaluates the materials’ stability under ambient environmental conditions. Unlike traditional halides with two to three metal elements, these newly developed perovskite halides consist of five or more principal metal elements in nearly equal concentrations. The workplan features a closed feedback loop between theory and experiment and focuses on materials advancement by performing theoretical predictions, developing synthesis methods, characterizing optoelectronic properties, and evaluating stability under exposure to gases, light, and heat. New perovskite halide materials discovered from this project could lead to a wide variety of optoelectronic applications including solar cells, light-emitting devices, photodetectors and lasers, photoelectrochemical catalysts, radiation detectors, and sensors. This research allows project participants from interdisciplinary programs at these two universities to interact and contribute to technology development within Maine and Alabama. Three Ph.D. graduate students and six undergraduates are trained to acquire skills and competency in the three foundational pillars of computation, experiments, and data analysis which are key attributes for the next-generation workforce. STEM outreach and education activities disseminated to K-12 students, high-school teachers, and the general public within Maine and Alabama are aimed at conveying how collaborative energy-materials design-driven research is relevant to addressing societal challenges. PART 2: TECHNICAL SUMMARYThis project, which is jointly funded by the Solid State and Materials Chemistry program in the Division of Materials Research and the Established Program to Stimulate Competitive Research (EPSCoR), aims to computationally design and experimentally realize a new class of lead-free perovskite halide materials with enhanced thermodynamic and environmental stability along with desired optoelectronic properties. Entropy-stabilized perovskite halides (ESPHs) containing five or more principal metal elements are investigated for enhanced optoelectronic properties and stable environmental performance. The key hypothesis is that the configurational entropy of mixing plays a dominant role in stabilizing a single-phase crystalline ESPH structure. The validation of this hypothesis not only provides a new experimentally controllable pathway to design more stable perovskite halide materials but also yields unique composition-structure-property relationships that are absent when chemical order prevails. Specific objectives are to (i) predict the combinations of metal elements that can give rise to stable ESPHs using high-throughput first-principles calculations, (ii) synthesize the predicted ESPHs using the solid-state solution, hydrothermal, and solvent precipitation methods, (iii) characterize the compositional, structural and optoelectronic properties of the synthesized ESPHs, and (iv) evaluate and analyze the stabilities of experimentally synthesized ESPHs under various laboratory environments including humidity, oxidizing/reducing gases, and heat. New ESPHs from this project are poised to substantially expand the chemical space of perovskite halides, providing more capabilities to tune and tailor materials properties of interest (such as lattice parameter, bandgap, optical absorption strength, and conductivity) and render high potential for a wide variety of optoelectronic applications including solar cells, light-emitting devices, photoelectrochemical catalysts, photodetectors and lasers, radiation detectors, and sensors.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.