Femtosecond laser ablation for fabrication of high resolution and multicolor perovskite nanocrystals light-emitting diodes

The development of perovskite nanocrystals (NCs) based light-emitting diodes (LEDs) are looking for new patterning technology, which is crucial for realization of high resolution and full color displays. Herein, femtosecond (fs) laser processing is introduced for fabrication of patterned and pixelated CsPbBr₃ and CsPbI₃ NCs films. The rapid removal of NCs in target area under fs laser radiation is demonstrated, proving the effectiveness of fs laser ablation for patterning of perovskite NCs. As a result, pixelated CsPbI₃ and CsPbBr₃ NCs films with pixels per inch (PPI) up to 1693 and clear boundaries are successfully obtained. Then, electroluminescent (EL) devices with bilayered emission layers (CsPbBr₃ and CsPbI₃ NCs) are fabricated for exploration of multicolor LEDs. Through understanding into the carrier recombination dynamics, the dominant red emissions in these EL devices are well explained. Finally, multicolor EL devices with green and red pixels are realized with one-step fs laser ablation on CsPbI₃ NCs because of their priority in carrier recombination. Moreover, the as-fabricated multicolor EL devices achieve a maximum luminance of 488 cd/m² and external quantum efficiency of 7.7%, demonstrating great potential of fs laser ablation towards pixelated full color perovskite NCs based LEDs.