Sol-gel deposited gallium-doped zinc oxide electrode for polymer light-emitting diode applications

We have made a sol-gel deposited gallium-doped zinc oxide (GZO) film as a transparent conductive anode in polymer light-emitting diode (PLED) applications. The GZO films were obtained by spin-coating GZO precursor solutions followed by consecutive thermal annealing in the air and in the hydrogen-rich atmosphere. The resistance of GZO film was reduced to similar to 100 Omega/square after thermal annealing in the hydrogen environment. Its surface roughness was sufficiently low (1.159 nm RMS) for depositing other polymer layers. We have fabricated PLEDs with quartz substrate/solution-processed GZO electrode (anode)/PEDOT: PSS (HITL)/SPG-01T (Green polymer light-emitting material purchased from Merck, EML)/Ca (EIL)/Al (Cathode). The fabricated devices showed current efficiency of 3.06 cd/A and power efficiency of 1.25 lm/W at luminance of 1000 cd/m(2).