All-inorganic Quantum-dot Light-emitting Diodes Based on Perovskite Emitters with Low Turn-on Voltage and High Humidity Stability
Recently, both light-to-electricity and electricity-to-light conversion efficiencies of perovskite achieved breakthrough, e.g. 22.1% for solar cells and 11.7% for light-emitting diodes (LEDs), so the next fatal problem towards practical application, the device stability, became the key issue in this field. Here, for the first time, we report the all-inorganic LEDs including inorganic perovskite emitters (CsPbBr3) and inorganic charge transport layers (CTLs) with emphasis on the significantly improved device stability. The quantum dot LEDs (QLEDs) were fabricated according to ITO/NiO/CsPbBr3 QDs/ZnO/Al device confriguration. On the one hand, the all-inorganic LED lifetime under 65% humidity corresponding to 70% electroluminescence (EL) conservation rate can be improved up to 3.5 times when compared with LEDs adopting conventional organic CTLs due to the intrinsic chemical stability of these inorganic CTLs and their hydrophobic surfaces. Furthermore, as a surprise, the bare all-inorganic LED without encapsulation can work in water for about 20 seconds, which is over 10 times more sustainable than the organic-inorganic LED, which proves the excellent water-isolation ability. On the other hand, the all-inorganic QLEDs show the lowest turn-on voltage of 2.4 V among all the reported CsPbBr3 QLEDs because the inorganic CTLs possess well-matched energy band alignments with CsPbBr3, and hence resulting in efficient carrier injection. This work paves a way, constructing all-inorganic devices, for the stable perovskite photovoltaic and light-emitting devices.