CsPbBr₃ Perovskite Quantum Dot Light‐Emitting Diodes Using Atomic Layer Deposited Al₂O₃ and ZnO Interlayers

Abstract

Most CsPbBr 3 perovskite quantum dot light‐emitting diodes (PQD‐LEDs) are fabricated with an inverted device structure where hole transport/injection layers are vacuum‐deposited on top of ITO/ZnO (as an electron transport layer (ETL))/PQDs. Standard device architecture of PQD‐LEDs enables a solution‐process of device fabrication; however, the spin‐coating of ZnO ETL dissolved in polar solvent results in decreasing photoluminescence (PL) of PQDs because of PQD destabilization in polar medium. Herein, CsPbBr 3 PQD‐LEDs are fabricated by depositing Al 2 O 3 and ZnO via atomic layer deposition (ALD) to avoid damages originating from the polar solvent during ZnO ETL spin‐coating. Low temperature ALD is adopted to prevent the coarsening of the CsPbBr 3 PQDs. A thicker Al 2 O 3 interlayer can prevent PL quenching, but an excessively thick interlayer hinders electron transport due to the insulating nature of Al 2 O 3 . ZnO is sequentially deposited on Al 2 O 3 interlayer via ALD, and therefore Al 2 O 3 /ZnO bilayer structure is used because of its better electron transporting ability and higher power efficiency in PQD‐LED devices compared with Al 2 O 3 ‐only devices.