Atomic-Level Insight into Photoinduced Transformations in Perovskite Optoelectronics

气候紧急状态使得寻找新的更高效的能源材料势在必行。金属卤化物钙钛矿材料(MHPS)是一类高效、经济、轻质的太阳能电池和发光二极管材料。其中一个关键挑战是，这些材料对环境条件非常敏感，在氧气、湿度和光照下很容易发生化学变化。虽然这些过程可能是有害的，也可能是有益的，但人们对它们的原子级机制知之甚少，这使得理性地设计缓解策略变得困难。PhotoPero核磁共振通过使用高效合成方法和固态魔角旋转(MAS)核磁共振(核磁共振)相结合来解决这一挑战。该项目将研究MHP表面与环境气体的反应性，确定与光电子学相关的各种结构不同材料的表面物种的化学性质，包括铅和无铅钙钛矿和双钙钛矿。下一步，它将制定一项战略，以直接与光电子学、完整的光电子器件相关的形式从MHPS获取原子级(本地)结构数据。它将开发一种策略，在不同的大气中照亮MHPS，并研究由此产生的转变的微观机制。最后，它将阐明设备在光照下发生的局部结构变化，使用OPANDO核磁共振。在这里获得的综合知识将有助于制定合理的设计原则，使钝化剂的设计具有更好的特性。这种局部结构表征框架将为最成功的材料提供支持的微观洞察，自然地结合有意和无意的表面钝化、光诱导效应以及与邻近器件层的相互作用的效果。

The climate emergency makes the search for new more efficient energy materials imperative. Metal halide perovskites (MHPs) belong to a class of materials promising highly efficient, affordable, and lightweight solar cells and light emitting diodes. One of the key challenges is that these materials are remarkably sensitive to ambient conditions and readily undergo chemical transformations in the presence of oxygen, humidity and under illumination. While these processes can be either pernicious or beneficial, very little is known about their atomic- level mechanism, which makes it difficult to rationally design mitigation strategies. PhotoPeroNMR sets out to address this challenge by using a combination of highly efficient synthetic approaches and solid-state Magic Angle Spinning (MAS) Nuclear Magnetic Resonance (NMR). The project will study the reactivity of MHP surfaces with ambient gases, identify the chemistries of the surface species across a wide range of structurally diverse materials relevant to optoelectronics, including lead and lead-free perovskites and double perovskites. Next, it will develop a strategy to access atomic-level (local) structural data from MHPs in their form directly relevant to optoelectronics, intact optoelectronic devices. It will develop a strategy to illuminate MHPs in a variety of atmospheres and study the microscopic mechanism of the resulting transformations. Finally, it will elucidate the local structural changes taking place in devices under illumination using operando NMR. The combined knowledge obtained here will serve to formulate rational design principles enabling the design of passivation agents with improved characteristics. This local structure characterization framework will provide an underpinning microscopic insight into the most successful materials, naturally combining the effects of intentional and unintentional surface passivation, photoinduced effects, and interactions with the neighboring device layers.