Improving the efficiency and stability of inorganic red perovskite light-emitting diodes using traces of zinc ions

Metal halide perovskite light-emitting diodes (PeLEDs) have been recognized as emerging candidates for next-generation solution-processed electronic display technology, and great progress has been made in recent years. However, their poor operational stability is yet to be solved. Here, we present a reformative all-inorganic red-emission PeLED based on the passivation effect caused by the incorporation of zinc ions into perovskites for enhancing the efficiency and operational stability. A high-quality quasi-two-dimensional perovskite CsPbI3-xBrx thin film with good crystallinity is obtained, benefiting from the combination of large organic ammonium ions (PEA+ ions) and inorganic salt zinc iodide (ZnI2). As a result, ZnI2-passivated CsPbI3-xBrx PeLEDs emitting at 666 nm show a maximum external quantum efficiency of 9.93% and a maximum brightness of 4258 cd m-2. More importantly, the PeLEDs achieve a long half-lifetime of about 2667 h at an initial luminance of 100 cd m-2. This work provides a facile method to obtain stable and efficient red-emission PeLEDs.