Improving electron injection in all-inorganic perovskite light-emitting diode via electron transport layer modulation

Interface engineering of the perovskite light emitting diodes (PeLED) and the balance between electron and hole injections are essential to optimize the device performance. In this paper, we fabricated the PeLEDs with the structure of ITO/NiO/CsPbBr 3 QDs/ZnO/Ag and used an Al-doped ZnO (AZO) as inserting layer between the ZnO and Ag cathode. It is found that the electron injection can be remarkably modulated by the thickness ratio of ZnO to AZO. Consequently, the maximum luminance and external quantum efficiency of green PeLED with ZnO/AZO (15 nm/15 nm) show a 1.9-fold and 1.7-fold enhancement as compared to the device only with ZnO. At the same time, the turn-on voltage of the device is also reduced from 3.5 V to 2.7 V.