TOSPEL Transient operando spectroscopy of perovskite nanocrystal LEDs

满足对环境影响有限的照明需求的大幅增长有赖于提供节能照明系统的技术发展。金属卤化物钙钛矿已经成为一种新的半导体类别，它创造了机会，彻底改变了我们将电能转化为光的方式。钙钛矿型纳米晶发光二极管(LED)具有制作成本低、效率高、带隙可调、颜色纯度高等优点，具有成为下一代LED的巨大潜力。尽管钙钛矿型纳米晶LED具有许多优点，但不可避免的纳米晶尺寸分布、形状差异和表面态导致多种动态过程并存，从而影响LED的光电性能和工作稳定性。该项目名为“钙钛矿型纳米晶体发光二极管的瞬时操作面光谱”(TOSPEL)。将周期电激励和飞秒光脉冲相结合的新型超快吸收和发射光谱技术将被设计并应用于钙钛矿型纳米LED。申请者将在麻省理工学院加入巴文迪集团(离开阶段)，以合成钙钛矿纳米晶体并制造具有理想光学性能的纳米晶体LED，这些纳米晶体LED将用于使用巴文迪集团最新设计的瞬变操纵面发射技术进行超快动力学研究。在返回阶段，申请者将加入剑桥大学的斯特兰克斯小组，设计和实施瞬时吸收光谱，以研究激子、载流子、陷阱和自旋之间的相互作用以及工作LED中的复合机制。这些结果将对LED的光物理有一个新的全面的认识，并为其进一步的发展提供指导。

Meeting the substantially growing demand for lighting with limited environmental impact relies on technological developments delivering an energy-efficient lighting system. Metal-halide perovskites have emerged as a new class of semiconductors that creates opportunities to revolutionize the way we convert electrical energy into light. Perovskite nanocrystal light-emitting diodes (LEDs) have enormous potential to be the next generation of LEDs due to their low fabrication cost, high efficiency, bandgap tunability, and high color purity. Despite the advantages of perovskite nanocrystal LEDs, the inevitable nanocrystal size distribution, shape difference, and surface states lead to the co-existence of multiple dynamic processes that influence the optoelectronic properties and the operational stability of the LEDs. This project is titled "Transient operando spectroscopy of perovskite nanocrystal LEDs" (TospeL). Novel ultrafast absorption and emission spectroscopic techniques combining periodic electrical excitations and femtosecond optical pulses will be designed and applied to perovskite nanocrystal LEDs. The applicant will join the Bawendi Group at MIT (outgoing phase) to synthesize perovskite nanocrystals and fabricate nanocrystal LEDs with desirable optical properties, which will be used for ultrafast dynamics studies using newly designed transient operando emission techniques in the Bawendi Group. For the return phase, the applicant will join the Stranks Group at University of Cambridge to design and implement transient absorption spectroscopy to investigate the interactions between excitons, carriers, traps, and spin as well as the recombination mechanisms in working LEDs. These results will give a new comprehensive understanding of LEDs photophysics and provide guidance for their further development.