Theoretical exploration of p-doped BiFeO3: models, screening, and applications

该项目有三个相互交织的研究目标，围绕着p掺杂BiFeO(BFO)的研究，目的是为BFO的p/n结找到合适的成分，以便实现氧化物电子学和光伏。在第一个研究目标中，计划通过调整生产运行的有效理论模型(如混合DFT和DFT+U)的参数来评估和提炼有效的理论模型，以便重现从高精度基准计算(包括激子效应的多体计算)获得的结果。其次，通过标准密度泛函理论研究了掺杂阳离子对BFO电子结构和极化的影响，从而筛选出适合BFO中p型掺杂的掺杂阳离子。对最有希望的候选人的描述将用项目第一部分中获得的改进方法进行改进。此外，利用东道主研究所已经建立的合作，在一项跨学科研究中设想了最佳掺杂候选者的制造和实验测试，这将使在进一步步骤中制造BFO p/n结成为可能。该项目的这一部分将以这样一种方式进行，即能够找到有关掺杂离子的趋势，从而使所获得的结果能够转移到类似的铁电金属氧化物上。在最后一个研究目标中，先前获得的结果将通过利用主办方在描述所研究的系统和方法的本体光伏效应(BPVE)时的专业知识来进一步处理。这意味着，我想要研究p掺杂和波函数的质量对计算的移位电流的影响，这被Rappe教授和他的团队证明是BPVE的主要机制。总之，该项目涵盖了p掺杂BFO的设计和研究，从基础研究到开发合适的、更准确但可行的理论描述，通过密集但高效的筛选来确定有希望的候选者，直到所开发材料的实验合成和器件制造。因此，该项目提供了一种系统的、智能的p掺杂BFO材料设计和结果，这些结果可以转移到类似的宿主结构中，有助于设计和制造金属氧化物p/n结，从而有助于未来的氧化物电子和光伏。

The project has three intertwined research objectives, centered around the investigation of p-doped BiFeO3 (BFO) with the aim of finding suitable compositions for BFO p/n-junctions, in order to enable oxide electronics and photovoltaics. In the first research objective, it is planned to evaluate and refine effective theoretical models for production runs (such as hybrid-DFT and DFT+U) by adjusting their parameters in order to reproduce results obtained from highly accurate benchmark calculations (many body calculations including excitonic effects). Secondly, I want to screen suitable dopant cations for p-type doping in BFO with respect to their induced changes on the electronic structure and the polarization of BFO by standard DFT. The description of the most promising candidates will be refined with the refined methods obtained in the first part of the project. In addition, fabrication and experimental testing of the best dopant candidates is envisioned within an interdisciplinary study using already established collaborations at the host institute, which will enable the fabrication of BFO p/n-junctions in further steps. This part of the project will be carried out in a way that will allow to find trends with respect to the dopant ions, which in turn will allow the transfer of the obtained results to similar ferroelectric metal oxides. In the last research objective, the previously obtained results will be further processed by employing the expertise of the host group in the description of the bulk-photovoltaic effect (BPVE) to the studied systems and methods. This means, I want to investigate the effects that p-doping and the quality of the wave function have on the computed shift current, which was shown to be the dominant mechanism of the BPVE by Prof. Rappe and his group.In summary, the project covers the design and investigation of p-doped BFO from basis research and the development of a suitable, more accurate but feasible theoretical description, over intense but efficient screening in order to identify promising candidates, up to experimental synthesis of the developed materials and device fabrication. Thus, the project provides a systematic, intelligent material design of p-doped BFO and results that are transferable to similar host structures, contributing to the design and fabrication of metal oxide p/n-junctions and, thus, future oxide electronics and photovoltaics.