Accelerating Energy Funnel and Charge Transport of Quasi-2D Perovskites for Efficient Sky Blue- and White-Light-Emitting Devices

Additive engineering is an effective strategy to enhance the performance of perovskite light-emitting devices. Herein, the introduction of hypophosphorous acid (HPA) is shown to increase the three-dimensional (3D) phase content in quasi-two-dimensional perovskites. HPA effectively passivates metallic Pb defects and enhances the crystallinity to increase the luminescence efficiency. In addition, HPA addition promotes the charge transport of quasi-two-dimensional perovskites due to increased 3D phase content and enhanced crystallinity. Consequently, HPA incorporation greatly increases the maximum external quantum efficiency and luminance of the related perovskite light-emitting devices. In particular, the perovskite/organic white-emitting devices, consisting of the blue-emitting HPA-modified quasi-two-dimensional perovskite and orange-emitting organic layers, show the maximum external quantum efficiency of 6.5% and maximum luminance of 2700 cd m(-2), which represent a large improvement over the previously reported analogous devices.