Laser ablation process of CsPbBr ₃ heterostructures for light-emitting diode applications

We investigated a vacuum thin-film process using laser ablation to fabricate heterostructures of halide perovskite CsPbBr3 for light-emitting diode (LED) applications. A CsPbBr3 single crystal synthesized via inverse temperature crystallization was used as the target material for pulsed laser deposition. CsPbBr3 films were deposited at 150°C, 200°C and 250°C. Structural and optical analysis has revealed that the optimum temperature is 200°C, which display the highest crystallinity and photoluminescence emission efficiency. Time-resolved microwave photoconductivity characterization revealed that the CsPbBr3 film exhibited a high effective mobility of 2.47 cm2/Vs and long photocarrier lifetime of 16.5 μs. The lifetime is comparable to that of bulk CsPbBr3 single crystals. This indicates that the polycrystalline CsPbBr3 film had a low density of defect structures that promote nonradiative recombination. Furthermore, we applied this process to fabricate a LED device using halide perovskite heterostructures. This resulted in a strong green electroluminescence emission. The laser ablation process using ultraviolet and infrared light is suitable for forming heterostructures with an electron transportation layer of oxide Mg0.3Zn0.7O film and a hole transportation layer of an organic α-NPD film. The film synthesis process is likely to be effective for evaluating heterointerfaces of various materials displaying remarkable crystallinity without exposure to air.