In Situ Light-Initiated Ligands Cross-Linking Enables Efficient All-Solution-Processed Perovskite Light-Emitting Diodes

Solution process has been considered to be an effective method to fabricate an emitting layer (EML) in light-emitting diodes (LEDs). However, the fabrication of the charge transport layer (CTL) above the perovskite EML by solution processing is challenging. Herein, we incorporated polymerizable molecules, conjugated linoleic acid (CLA), as surface ligands to passivate perovskite QDs. The polymerized CLA can create a cross-linked QD film, which allows the solution deposition of subsequent CTLs. The theoretical calculations reveal that the binding energy of polymerized CLA with QDs increased, and the strong ligands' binding state can better passivate the surface and improve the stability of QDs. As a result, all-solution-processed multilayer perovskite LEDs were fabricated with performance of a max luminance of 2470 cd/m(2) for CsPbBr3-based devices and a peak EQE of 2.67% for CsPbI3-based devices. These results demonstrate that the in situ light-initiated ligands cross-linking can be an effective strategy in all-solution-processed optoelectronic devices.