All-Solution-Processed Perovskite Light-Emitting Diodes Based on a Thiol-Modified ZnO Electron-Transporting Layer

All-solution-processed perovskite light-emitting diodes (LEDs) have the potential to be inexpensive and easily manufactured on a large scale without requiring vacuum thermal deposition of the emissive and charge transport layers. Zinc oxide (ZnO), which possesses superior optical and electronic properties, is commonly used in all-solution-processed optoelectronic devices. However, the polar solvent of ZnO inks can corrode the perovskite layer and cause severe photoluminescence quenching. In this work, we report the successful dispersion of ZnO nanoparticles in nonpolar n-octane by controlling the surface ligands from acetates to thiols. The nonpolar ink prevents the destruction of perovskite films. In addition, thiol ligands upshift the conduction band energy level, which also helps inhibit exciton quenching. Consequently, we demonstrate the fabrication of high-performance all-solution-processed green perovskite LEDs with a brightness of 21 000 cd/m2 and an external quantum efficiency of 6.36%. Our work provides a ZnO ink for fabricating efficient all-solution-processed perovskite LEDs.