Color tunability of perovskite light-emitting diodes (PeLEDs) by mixed halide compositional engineering is one of the primary intriguing characteristics of PeLEDs. However, mixed halide PeLEDs are often susceptible to color red-shifting caused by halide ion segregation. In this work, strongly quantum-confined perovskite nanowires (QPNWs) made of CsPbBr3 are grown in nanoporous anodic alumina templates using a closed space sublimation process. By tuning the pore size with atomic layer deposition, QPNWs with a diameter of 6.6 to 2.8 nm have been successfully obtained, with continuous tunable photoluminescence emission color from green (512 nm) to pure blue (467 nm). To better understand the photophysics of QPNWs, carrier dynamics and the benefit of alumina passivation are studied and discussed in detail. Eventually, PeLEDs using various diameters of CsPbBr3 QPNWs are successfully fabricated with cyan color (492 nm) PeLEDs, achieving a record high 7.1% external quantum efficiency (EQE) for all CsPbBr3-based cyan color PeLEDs. Sky blue (481 nm) and pure blue (467 nm) PeLEDs have also been successfully demonstrated, respectively. The work here demonstrates a different approach to achieve quantum-confined one-dimensional perovskite structures and color-tunable PeLEDs, particularly blue PeLEDs.
Keywords: anodized alumina; atomic layer deposition; blue emission LEDs; nanowires; perovskite; quantum confinement.