Influence of gallium-doped zinc-oxide thickness on polymer light-emitting diode luminescence efficiency.

Conducting atomic force microscopy and scanning surface potential microscopy were used to study the local electrical properties of gallium-doped zinc oxide (GZO) films prepared by pulsed laser deposition (PLD) on a polyimide (PI) substrate. For a PLD deposition process time of 8 min, the root-mean-square roughness, coverage percentage of the conducting regions, and mean work function on the GZO surface were 2.33 nm, 96.6%, and 4.82 eV, respectively. When the GZO/PI substrate was used for a polymer light-emitting diode (PLED), the electroluminescence intensity increased by nearly 20% compared to a standard PLED, which was based on a commercial-ITO/glass substrate.