Department of Materials Science and Engineering, and California NanoSystems Institute, University of California, Los Angeles, CA, 90095, USA.
Department of Materials Science and Engineering, Korea Advanced Institute of Science and Technology, 291 Daehak-ro, Yuseong-gu, Daejeon, 34141, Republic of Korea.
Nat Commun. 2019 Jan 31;10(1):520. doi: 10.1038/s41467-019-08455-z.
Manipulation of grain boundaries in polycrystalline perovskite is an essential consideration for both the optoelectronic properties and environmental stability of solar cells as the solution-processing of perovskite films inevitably introduces many defects at grain boundaries. Though small molecule-based additives have proven to be effective defect passivating agents, their high volatility and diffusivity cannot render perovskite films robust enough against harsh environments. Here we suggest design rules for effective molecules by considering their molecular structure. From these, we introduce a strategy to form macromolecular intermediate phases using long chain polymers, which leads to the formation of a polymer-perovskite composite cross-linker. The cross-linker functions to bridge the perovskite grains, minimizing grain-to-grain electrical decoupling and yielding excellent environmental stability against moisture, light, and heat, which has not been attainable with small molecule defect passivating agents. Consequently, all photovoltaic parameters are significantly enhanced in the solar cells and the devices also show excellent stability.
在多晶钙钛矿中，晶界的调控对于太阳能电池的光电性能和环境稳定性至关重要，因为钙钛矿薄膜的溶液处理不可避免地会在晶界处引入许多缺陷。尽管基于小分子的添加剂已被证明是有效的缺陷钝化剂，但它们的高挥发性和高扩散性不能使钙钛矿薄膜具有足够的抗恶劣环境的能力。在这里，我们通过考虑分子结构为有效的分子设计规则。由此，我们引入了一种使用长链聚合物形成大分子中间相的策略，从而形成了聚合物-钙钛矿复合交联剂。交联剂的作用是桥接钙钛矿晶粒，最大限度地减少晶粒间的电去耦，从而获得对湿气、光照和热的优异环境稳定性，这是小分子缺陷钝化剂所无法达到的。因此，太阳能电池的所有光伏参数都得到了显著提高，而且这些器件也表现出了优异的稳定性。
