Highly stable cesium lead iodide perovskite quantum dot light-emitting diodes.

Recently, all-inorganic perovskites such as CsPbBr and CsPbI, have emerged as promising materials for light-emitting applications. While encouraging performance has been demonstrated, the stability issue of the red-emitting CsPbI is still a major concern due to its small tolerance factor. Here we report a highly stable CsPbI 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 L 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 CsPbI QDs for stable red LEDs, and suggest the feasibility for electrically pumped perovskite lasers with further device optimizations.