Utilizing ALD to fabricate ZnO ETL to improve the luminous efficiency of perovskite light-emitting diodes

In this work, we demonstrate an approach to fabricate perovskite light-emitting diodes (PeLEDs) by integrating atomic layer deposition (ALD) and single-source vapor deposition (SSVD), which can operate at low voltages without the hole transport layer, thereby achieving high luminescence. This study successfully eliminated the heterostructure in the CsPbBr₃ emitting layer through thermal annealing, thereby improving the quality and crystallinity of the film. We also employ the ALD process to produce zinc oxide (ZnO) as the electron transport layer (ETL) to enhance the electron transport capability of the PeLEDs. By combining the optimized CsPbBr₃ emitting layer with ZnO ETL, PeLEDs devices were successfully fabricated. These PeLEDs operate at just 2.67 V, producing high-purity green light (CIE 1931 coordinates: (0.1432, 0.8015)) at 17,661 cd m^{- 2}, a significant 23% improvement in brightness compared to the device without ZnO ETL. It is worth noting that the green PeLEDs produced in this study only requires two commercially available 1.5 V batteries to activate and achieve maximum brightness, effectively overcoming the issue of excessively high voltage in PeLEDs. There is potential for its application in the field of PeLEDs production in the future.