Lead-free Double Perovskite Materials for Photovoltaic Applications

卤化铅钙钛矿材料在能量转换领域产生了巨大的兴奋，因为它们为光伏（PV）和发光应用提供了有前途的性能。然而，卤化铅钙钛矿的缺点是对水分不稳定，器件性能不可靠以及铅的固有毒性。虽然太阳能电池板的封装可以防止铅的释放，但铅必须在这些太阳能电池的使用寿命结束时收集。因此，未来钙钛矿太阳能电池的理想解决方案是生产高效稳定的无铅太阳能电池。我们提案的目标是探索和了解无铅双钙钛矿在光伏应用中的潜力，并为光伏应用中新型无毒和稳定的钙钛矿材料的设计提供概念工具。首先对参考材料Cs2AgBiBr6的单晶和薄膜进行理论和实验研究，研究其光电特性和潜在的不良损耗机制，然后系统地探索无毒无铅双钙钛矿的结构相空间。为此，我们将系统地用高水平理论计算建议的最有希望的元素代替参考物质的成分。这些新合成的无铅钙钛矿晶体和薄膜的光学和电子特性将再次进行实验和理论研究。最后，将最有前途的双钙钛矿材料应用到太阳能电池中，并进行详细的电子表征，为新合成的无铅双钙钛矿材料的进一步优化提供指导。

Lead halide perovskite materials have created enormous excitement in the context of energy conversion as they offer promising properties for photovoltaic (PV) and light emitting applications. However, lead-halide perovskites suffer from drawbacks such as instability toward moisture, unreliable device performance and the inherent toxicity of lead. Although the encapsulation of solar panels can prevent the release of lead, lead will have to be collected at the end of the operational lifetime of those solar cells. The ideal solution for future perovskite solar cells therefore is to produce efficient and stable lead-free solar cells. The goal of our proposal is to explore and understand the potential of lead-free double perovskites for photovoltaic applications, and to provide conceptual tools for the design of new nontoxic and stable perovskite materials for PV applications. First single crystals and films of the reference material Cs2AgBiBr6 will be studied theoretically and experimentally regarding their optoelectronic properties and potential undesirable loss mechanisms, followed by a systematic exploration of the structural phase space of nontoxic lead-free double perovskites. To this end, we will systematically substitute the constituents of the reference material with the most promising elements, which will be suggested by high level theoretical calculations. The optical and electronic properties of those newly synthesized lead-free perovskite crystals and films will then again be studied experimentally and theoretically. Finally, the most promising double perovskite materials will be implemented into solar cells, followed by a detailed electronic characterization to provide guidance for further optimization of the newly synthesized lead-free double perovskite materials.