All-Solution-Processed\nMultilayered White Polymer\nLight-Emitting Diodes (WPLEDs) Based on Cross-Linked [Ir(4-vb-PBI)<sub>2</sub>(acac)]

All-solution-processed\nmultilayered white polymer light-emitting\ndiodes (WPLEDs) are promising candidates for low-cost and large-area\nflexible full-color flat-panel displays and solid-state lighting.\nHowever, it is still challenging to improve their performance. In\nthis work, based on an elegant strategy of orthogonal materials, the\nutilization of the cross-linked Ir³⁺ polymer film <b>poly­(NVK-<i>co</i>-[Ir­(4-vb-PBI)</b>_<b>2</b><b>(acac)]-</b><i><b>co</b></i><b>-NVK)</b> (<b>NVK</b> = <i>N</i>-vinyl-carbazole; <b>4-vb-HPBI</b> = 1-(4-vinylbenzyl)-2-phenyl-1<i>H</i>-benzo­[<i>d</i>]­imidazole; and <b>Hacac</b> = acetylacetone)\nas the emitting layer (EML) between a hydrophilic polymer film poly­(3,4-ethylenedioxythiophene):poly­(styrenesulfonate)\n(<b>PEDOT:PSS</b>) as the hole injection layer (HIL) and a hydrophobic\npolymer film <b>poly­(vinyl-PBD)</b> (<b>vinyl-PBD</b> =\n2-(4-(<i>tert</i>-butyl)­phenyl)-5-(4′-vinyl-[1,1′-biphenyl]-4-yl)-2,5-dihydro-1,3,4-oxadiazole)\nas the electron transport layer (ETL) led to the successful fabrication\nof reliable all-solution-processed multilayered WPLEDs. The device\nexhibits a η_CE^Max of 18.19 cd/A, a η_PE^Max of 8.16 lm/W, and a η_EQE^Max of 9.32% with stable white light (Commission International\nDe L’Eclairage (CIE) coordinates <i>x</i> = 0.269–0.283, <i>y</i> = 0.317–0.330; corrected color temperatures (CCTs)\nof 7237–8199 K, and CRIs (color rendering indices) of 63–72)\nunder a wide applied-voltage range. Its high performance, especially\nwith record efficiencies among those of reported all-solution-processed\nWPLEDs, renders cross-linked Ir³⁺ polymers a new platform\nto all-solution-processed multilayered WPLEDs.