Drastically increased OLED device luminance (up to 15 000 cd/m2) and enhanced quantum efficiency (6×) are achieved by spin‐coating a siloxane‐derivatized hole injector (TPD‐Si2) onto an ITO surface. The silyl groups promote ITO–TPD interfacial cohesion, thus enabling more efficient hole injection. The Figure shows a polarized optical image of the TPD film morphology after annealing the bilayer structure (see also inside front cover).