Publication date: 14th January 2021
Unveiling the synergy effects of precursor stoichiometry and interfacial reactions on perovskite crystallization and optoelectronic device performance
Zhongcheng Yuan,* Zhangjun Hu, Sai Bai & Feng Gao
* zhongcheng.yuan@liu.se, Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, SE-58183, Sweden
Metal halide perovskites are emerging as promising semiconductors for cost-effective and high-performance light-emitting diodes (LEDs).[1, 2] Previous investigations have focused on the optimization of the emissive perovskite layer, e.g. through quantum confinement to enhance the radiative recombination or through defect passivation to decrease non-radiative recombination.[3, 4] However, an in-depth understanding of how the influence of local elements distribution on the perovskite crystallization, though of critical importance, is currently missing for perovskite optoelectronic devices. Here, we study precursor stoichiometry and interfacial reactions for high-performance perovskite LEDs, and establish useful guidelines for rational device optimization. We reveal that efficient deprotonation of the undesirable organic cations by a metal oxide interlayer with a high isoelectric point is critical to promote the transition of intermediate phases to highly emissive perovskite films. Based on our new understanding, we develop high-quality near-infrared (NIR) emissive formamidinium- cesium (FA-Cs) perovskite films at a low processing temperature.[5]