Effect of oxygen plasma treatment on CdSe/CdZnS quantum-dot light-emitting diodes

Red-light-emitting diodes (LEDs) were fabricated using CdSe/CdZnS quantum dots (QDs). During the device fabrication process, the oxygen plasma treatment of the indium tin oxide (ITO) surface was performed to improve the interfacial contact between the ITO anode and the hole injection layer. The device showed red emission at 622 nm, which was consistent with the dimensions of the QDs (band gap: 1.99 eV). The luminance was 108.77 cd/m(2) and the current density was 230.2 mA/cm(2) at an operating voltage of 7 V, when the oxygen plasma treatment was performed on the ITO surface. The luminance showed 207% improvement compared with that of LEDs fabricated without oxygen plasma treatment. These results suggested that the oxygen plasma treatment of the ITO surface improved the contact between ITO and PEDOT:PSS, and that the light emitting intensity was markedly improved. (C) 2014 The Japan Society of Applied Physics