Understanding and control over defects in halide perovskites through defect chemical studies combined with in situ optical characterization and detailed optical spectroscopy

通过缺陷化学研究结合原位光学表征和详细光谱来了解和控制卤化物钙钛矿的缺陷

• 批准号: 324052211
• 负责人: Professorin Dr. Anna Köhler
• 金额: --
• 依托单位: Lehrstuhl für Experimentalphysik II (Optoelektronik weicher Materie)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/324052211?language=en
• 关键词: Understanding; control; over; defects; halide

Due to the excellent optoelectronic properties of halide perovskites, their use as an efficient semiconductor material in many applications such as solar cells, light-emitting diodes, or in detectors for light, X-rays and gamma radiation is being discussed. A remarkable feature of halide perovskites in this context is their high tolerance and self-healing ability towards intrinsic ionic point defects. Nevertheless, these defects can affect the optoelectronic properties and, for example, cause ions to move through the halide perovskite when a potential difference is applied, leading to efficiency losses and degradation of the properties of optoelectronic devices based on halide perovskites. Therefore, the goal of this project is to gain a deep understanding of how various point defects in halide perovskites affect their optoelectronic properties and to understand how point defect concentrations can be tuned through controlled modifications of the perovskites. Key to achieving these goals is the combination of defect chemistry studies with optical measurements on halide perovskite samples with well-defined properties. The basic investigations involve the precise setting of an iodine partial pressure that leads to a thermodynamically defined interaction of the perovskites with iodine and thus to an equilibrium concentration of point defects that depends on the iodine partial pressure and the temperature. Such an approach is standard for oxide perovskites. In the previous project, it was also successfully demonstrated for methylammonium lead iodide that such an approach can work. In the proposed continuation project, the resulting point defect concentrations will be measured via the electrical conductivity, while the effects of these point defects on the optoelectronic properties will be studied directly via in-situ optical characterization, i.e., via the measurement of absorption and emission during film formation. In addition, doping will be used to target the defect concentrations in order to refine the defect chemical model and to determine quantitatively formation enthalpies. In order to make statements about the nature of the excited states and their relaxation, to identify defects and impurities, and to determine the location of defects in the band gap, powerful optical ex-situ measurement methods, such as transient absorption, temperature-dependent and time-dependent measurement of photoluminescence and thermally stimulated luminescence, are used. Overall, with the combination of in-situ and ex-situ investigations, a comprehensive defect chemical model will be established, which will allow to target defect concentrations, to understand the effects on optoelectronic properties, and to improve optoelectronic devices.

由于卤化物钙钛矿的优异的光电性能，它们在许多应用中作为有效的半导体材料的用途，例如太阳能电池、发光二极管或用于光、X射线和伽马辐射的检测器正在讨论中。在这种情况下，卤化物钙钛矿的显著特征是它们对本征离子点缺陷的高耐受性和自修复能力。然而，这些缺陷会影响光电性能，并且例如当施加电势差时导致离子移动通过卤化物钙钛矿，导致基于卤化物钙钛矿的光电器件的效率损失和性能劣化。因此，该项目的目标是深入了解卤化物钙钛矿中的各种点缺陷如何影响其光电性能，并了解如何通过钙钛矿的受控修改来调整点缺陷浓度。实现这些目标的关键是将缺陷化学研究与具有明确特性的卤化物钙钛矿样品的光学测量相结合。基本调查涉及碘分压的精确设置，其导致钙钛矿与碘的化学定义的相互作用，从而导致取决于碘分压和温度的点缺陷的平衡浓度。这种方法对于氧化物钙钛矿是标准的。在之前的项目中，也成功地证明了甲基铵碘化铅的这种方法是可行的。在拟议的继续项目中，将通过电导率测量产生的点缺陷浓度，而这些点缺陷对光电性能的影响将直接通过原位光学表征进行研究，即，通过测量薄膜形成过程中的吸收和发射。此外，掺杂将被用于目标的缺陷浓度，以完善的缺陷化学模型，并确定定量形成的缺陷。为了说明激发态及其弛豫的性质，识别缺陷和杂质，并确定带隙中缺陷的位置，使用了强大的光学非原位测量方法，例如瞬态吸收、温度依赖性和时间依赖性测量光致发光和热激发发光。总之，结合原位和非原位研究，将建立一个全面的缺陷化学模型，这将允许目标缺陷浓度，了解对光电性能的影响，并改善光电器件。