Highly Stable Cesium Lead Iodide Perovskite Quantum Dot Light-Emitting Diodes

Recently, all-inorganic perovskites such as CsPbBr₃ and CsPbI₃, have emerged as promising materials for light-emitting applications. While encouraging performance has been demonstrated, the stability issue of the red-emitting CsPbI₃ is still a major concern due to its small tolerance factor. Here we report a highly stable CsPbI₃ quantum dot (QD) light-emitting diode (LED) with red emission fabricated using an improved purification approach. The device achieved decent external quantum efficiency (EQE) of 0.21% at a bias of 6 V and outstanding operational stability, with a L₇₀ lifetime (EL intensity decreases to 70% of starting value) of 16 h and 1.5 h under a constant driving voltage of 5 V and 6 V (maximum EQE operation) respectively. Furthermore, the device can work under a higher voltage of 7 V (maximum luminance operation) and retain 50% of its initial EL intensity after 500 s. These findings demonstrate the promise of CsPbI₃ QDs for stable red LEDs, and suggest the feasibility for electrically pumped perovskite lasers with further device optimizations.