Efficient All-Blade-Coated Quantum Dot Light-Emitting\nDiodes through Solvent Engineering

Abstract

Blade-coating\nis a potential method for preparing all-solution-processed\nquantum dot light-emitting diodes (QLEDs) because of its high material\nutilization and large-scale preparation compatibility. However, it\nis a challenge to prepare uniform-emitting, high-performance QLEDs\nby blade coating because of film uniformity issues. Here, we report\nan efficient all-blade-coated QLED through solvent engineering. A\nbinary water/methanol solvent is used to decrease the surface tension,\nleading to uniform blade-coating poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate)\n(PEDOT:PSS) films. The binary solvent also enhances hole transport\nabilities because of phase separations and chain reorientations of\nPEDOT and PSS chains. The uniformity of a poly­(<i>N</i>-vinylcarbazole)\n(PVK) layer is also improved by using a chlorobenzene/toluene binary\nsolvent to facilitate the spontaneous spreading of the PVK solution\non the substrate. This enables the successful preparation of an efficient\nQLED with a maximum external quantum efficiency of 12.48%, which is\nabout 2.6 times the value of the QLED without solvent engineering.