GOALI: Doping Control and Processes in Metal Halide Perovskites

非技术描述：金属卤化物钙钛矿是指一类半导体，其最近在发光器件、光电探测器和太阳能电池中的使用中实现了优异的性能改进率。优异的性能和简便的溶液处理相结合，为低成本高性能电子器件提供了新的机会。虽然这些材料在电子器件中的应用取得了广泛的成功，但进一步的改进部分地受到如何控制半导体内的电载流子数量（称为掺杂）的缺乏理解的限制，这是建立器件操作的重要参数。通过创建一个广泛的跨学科项目，采用理论和实验方法，目前的研究旨在更好地了解掺杂过程，以控制这类重要的卤化物钙钛矿中的电子/空穴水平。通过实现该项目的目标，预计将设计出更高效的太阳能电池和发光器件以及更高性能的钙钛矿晶体管。本科生，研究生和博士后研究人员在多学科项目执行中发挥着关键作用，因此该项目在培养未来科学家方面发挥着至关重要的作用。作为一个GOALI项目，一个关键方面涉及扩大学生的经验，包括工业研究的曝光，以及创建一个链接到世界领先的材料表征能力在行业内。技术说明：使用本征/非本征晶体缺陷的半导体掺杂建立了决定光电特性的能级和载流子密度。例如，高性能光伏材料依赖于仔细的掺杂控制来修改电子特性并将器件性能提高到接近肖克利-奎瑟极限的水平。虽然金属卤化物钙钛矿最近受到了很多关注，但由于相关光伏性能的异常上升，目前对这类复杂离子半导体中掺杂的理解和探索仍然有限。该项目通过解决重要的掺杂相关问题为更可调的功能卤化物钙钛矿铺平了道路，例如：（1）金属卤化物钙钛矿的相对“软”性质是否可以为开发新的掺杂途径创造特殊的挑战和机会;（2）使用络合物而不是单独的离子是否可以增强掺杂的稳定性;和（3）在有机阳离子层内相对于在金属卤化物框架内的杂质掺杂存在什么样的分子掺杂机会？为了发展这种批判性的理解，该项目整合了材料合成，光电表征和理论方面的学术和工业研究，以研究钙钛矿半导体中的掺杂剂掺入和活化。该研究包括几个方面，包括：（1）理论/计算指导的新掺杂剂和掺杂工艺的开发，（2）混合钙钛矿中分子掺杂剂的探索，（3）使用掺杂的辐射复合的操纵和（4）由工业合作伙伴开发的独特电输运表征工具的应用，了解卤化物钙钛矿中的掺杂，并为复杂材料中的输运现象的未来研究提供框架。

Nontechnical Description: Metal halide perovskites refer to a class of semiconductors that have recently achieved an exceptional rate of performance improvement for use in light-emitting devices, photodetectors and solar cells. The combination of excellent performance and facile solution processing open new opportunities for low-cost high-performance electronic devices. While these materials have enjoyed extensive success for application in electronic devices, further improvement is limited in part by a lack of understanding of how to control the number of electrical carriers within the semiconductor (known as doping), which is a vital parameter for establishing device operation. By creating a broadly interdisciplinary project, employing both theory and experimental approaches, the current research seeks to develop a better understanding of doping processes for controlling the level of electrons/holes within this important class of halide perovskites. By achieving the goals of the project, novel designs of higher-efficiency solar cells and light-emitting devices, as well as higher-performance perovskite transistors are expected. Undergraduate, graduate and postdoc researchers play a pivotal role in the multidisciplinary project execution and the project therefore plays a vital role in training future scientists. As a GOALI project, a critical aspect involves broadening student experiences to include industrial research exposure, as well as creating a link to the world-leading materials characterization capabilities within industry. Technical Description: Semiconductor doping using intrinsic/extrinsic crystalline defects establishes the energy levels and carrier densities that determine optoelectronic properties. High-performance photovoltaic materials, for example, rely on careful doping control to modify the electronic properties and improve the device performance to levels approaching the Shockley-Queisser limit. Although metal halide perovskites have received much attention recently, due to the exceptional rise in associated photovoltaic performance, the current understanding and exploration of doping in this class of complex ionic semiconductors remains limited. This project paves the way for more tunable functional halide perovskites by addressing important doping related questions, such as: (1) can the relatively 'soft' nature of metal halide perovskites create special challenges and opportunities for development of new doping pathways; (2) can the use of complexes rather than individual ions enhance doping tenability; and (3) what opportunity for molecular doping exist within the organic cation layer versus impurity doping within the metal halide framework? In order to develop this critical understanding, the project integrates academic and industrial research in materials synthesis, optoelectronic characterization and theory to investigate dopant incorporation and activation in perovskite semiconductors. The research consists of several thrusts, including: (1) theory/computation-guided development of new dopants and doping processes, (2) exploration of molecular dopants in hybrid perovskites, (3) manipulation of radiative recombination using doping and (4) application of unique electrical transport characterization tools, developed by the industrial partner, to understand doping in halide perovskites and also to provide a framework for future study of transport phenomena in complex materials.