Enabling full-scale grain boundary mitigation in polycrystalline perovskite solids
Lichen Zhao, Pengyi Tang, Deying Luo, M. Ibrahim Dar, Felix T. Eickemeyer, Neha Arora, Qin Hu, Jingshan Luo, Yuhang Liu, Shaik M. Zakeeruddin, Anders Hagfeldt, Jordi Arbiol, Wei Huang, Qihuang Gong, Thomas P. Russell, Richard H. Friend, Michaël Grätzel, Rui Zhu
Abstract
There exists a considerable density of interaggregate grain boundaries (GBs) and intra-aggregate GBs in polycrystalline perovskites. Mitigation of intra-aggregate GBs is equally notable to that of interaggregate GBs as intra-aggregate GBs can also cause detrimental effects on the photovoltaic performances of perovskite solar cells (PSCs). Here, we demonstrate full-scale GB mitigation ranging from nanoscale intra-aggregate to submicron-scale interaggregate GBs, by modulating the crystallization kinetics using a judiciously designed brominated arylamine trimer. The optimized GB-mitigated perovskite films exhibit reduced nonradiative recombination, and their corresponding mesostructured PSCs show substantially enhanced device efficiency and long-term stability under illumination, humidity, or heat stress. The versatility of our strategy is also verified upon applying it to different categories of PSCs. Our discovery not only specifies a rarely addressed perspective concerning fundamental studies of perovskites at nanoscale but also opens a route to obtain high-quality solution-processed polycrystalline perovskites for high-performance optoelectronic devices.