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p掺杂BiFeO3 （BFO）的研究，目的是为BFO的p/n结找到合适的成分，以实现氧化物电子和光伏发电。在第一个研究目标中，计划通过调整参数来评估和完善生产运行的有效理论模型（如hybrid-DFT和DFT+U），以便重现从高精度基准计算（许多体计算包括激子效应）中获得的结果。其次，我想通过标准DFT对BFO中p型掺杂的电子结构和极化的变化来筛选合适的掺杂阳离子。最有希望的候选人的描述将细化与细化的方法在项目的第一部分获得。此外，利用在主办机构已经建立的合作关系，在跨学科研究中设想最佳掺杂候选物的制造和实验测试，这将使BFO p/n结的制造成为可能。该项目的这一部分将以一种允许发现有关掺杂离子的趋势的方式进行，这反过来将允许将获得的结果转移到类似的铁电金属氧化物。在最后一个研究目标中，将利用主机组的专业知识对先前获得的结果进行进一步处理，以描述所研究的系统和方法的bulk-photovoltaic effect （BPVE）。这意味着，我想研究p掺杂和波函数的质量对计算位移电流的影响，这被Rappe教授和他的团队证明是BPVE的主要机制。总而言之，该项目涵盖了p掺杂BFO的设计和研究，从基础研究和开发合适的，更准确但可行的理论描述，通过激烈但有效的筛选以确定有希望的候选者，直到开发材料的实验合成和设备制造。因此，该项目提供了一种系统的、智能的p掺杂BFO材料设计，其结果可转移到类似的主体结构中，有助于金属氧化物p/n结的设计和制造，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.