Tailoring Optoelectronic Processes in Metal Halide Perovskite via Piezoelectric and Piezo-Phototronic Effects

非技术性：金属卤化物钙钛矿代表了下一代太阳能电池的一类新兴材料。钙钛矿太阳能电池的功率转换效率在过去十年中从4%提高到24%。这些进展来自于控制薄膜的结晶、化学修饰和器件中的界面工程。虽然具有两个不同子电池的串联装置可以进一步提高效率，但是它们的制造是复杂的。这个项目采用了不同的策略。压电光子效应耦合机械应力、光吸收和电。该项目将利用这种效应生产性能显著改善的钙钛矿太阳能电池和光电探测器。该项目产生的知识将广泛影响这类有趣材料在太阳能电池，光电探测器和其他电子设备中的应用。这项工作也将加强纳米科学研究。高中教师的暑期研究机会将为将纳米材料科学和技术知识转移到高中课堂提供媒介。技术：本项目旨在利用压电效应和压电光电效应，对金属卤化物钙钛矿光电器件中的光电过程进行定制。这将增强金属卤化物钙钛矿的性能，即，太阳能电池中光电流和光电压的增加以及光电探测器中灵敏度的提高。(1)将研究钙钛矿薄膜在外加电场极化后的晶体形态、晶体取向以及电学性能。(2)将探索通过施加外部电场对钙钛矿太阳能电池和光电探测器的性能的极化引起的晶体形态和晶体取向的变化的影响。(3)压电光电效应的交替能带下的压电电位在钙钛矿/载流子传输层接口使外部应变的应用将被仔细检查。该项目的意义在于明智地探索压电效应对钙钛矿晶体形态和晶体取向以及钙钛矿/载流子输运层界面处的能带交替的影响，从而为高性能压电光电子调制的钙钛矿基器件提供光致激子解离，载流子输运和载流子收集的定制。由于极化电荷和光生载流子之间的压电光电耦合，由此产生的太阳能电池和光电探测器将表现出极大的性能改善，从而将基础科学发现转化为有益于社会的有用技术。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。

Nontechnical:Metal halide perovskites represent an emerging class of materials for next-generation solar cells. The power conversion efficiency of perovskite solar cells has increased from 4% to 24% over the past ten years. These advances have come through controlling the crystallization of thin films, chemical modification, and interface engineering in devices. Although tandem devices with two different sub-cells could further improve efficiency, their manufacturing is complicated. This project uses a different strategy. The piezo-photonic effect couples mechanical stress, light absorption, and electricity. The project will use this effect to produce perovskite-based solar cells and photodetectors with markedly improved performance. Knowledge generated by this project will broadly impact applications of this class of interesting materials with applications in solar cells, photodetectors, and other electronic devices. This work will also strength nanoscience research. Summer research opportunities for high school teachers will provide a medium for transferring nanomaterials science and technology knowledge to high school classrooms. Underrepresented female undergraduate students will participate in the research and the experience of high school students will be enriched.Technical:This project aims to tailor the optoelectronic processes in the metal halide perovskite-based optoelectronic devices by capitalizing on the piezoelectric effect and piezo-phototronic effect. This will enhance the performance of metal halide perovskites, i.e., increased photocurrent and photovoltage in solar cells and improved sensitivity in photodetectors. (1) The crystal morphology and crystal orientation as well as electrical properties of perovskite thin films upon poling by an external electric field will be interrogated. (2) The effect of poling-induced changes in crystal morphology and crystal orientation via the application of an external electric field on the performance of perovskite solar cells and photodetectors will be explored. (3) The piezo-phototronic effect on the alternation of energy band under piezopotential at the perovskite/carrier transport layer interfaces enabled by the application of external strain will be scrutinized. The significance of this project lies in judicious exploration of piezoelectric effect on perovskite crystal morphology and crystal orientation as well as energy band alternation at perovskite/carrier transport layer interfaces to render the tailoring of photo-induced exciton dissociation, charge carrier transport, and charge carrier collection for high-performance piezo-phototronics-modulated perovskite-based devices. The resulting solar cells and photodetectors will exhibit greatly improved performance due to the piezo-phototronic coupling between polarization charges and photogenerated carriers, thereby transitioning fundamental scientific discoveries into useful technologies that benefit society.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.