Fabrication of ink-jet printing quantum-dots light emitting diodes using optimization of co-solvent condition

In this research, we introduce the fabrication of ink-jet printed quantum-dot light emitting diodes (QLEDs) using optimization of co-solvent condition. Generally, in the fabrication of QLEDs, pinholes and dewetting on the surface of quantum-dot (QD) thin films in the pixel cause performance degradation of the QLEDs. To control this problem, we dispersed QDs with CdZnSeS structure at a concentration of 20 mg/ml in a 1: 2 mixture of hexane and dichlorobenzene (oDCB). In addition, for stabilization of the jetting process, cartridge meniscus and waveforms were optimized As a result, a uniform QD thin film was formed on a 240/tm x 60ftm bank pixel array. No pinholes or drying phenomena were found on the ink-jet printed QD thin film surface. The luminance, current efficiency, and quantum efficiency of the fabricated ink-jet printing QLEDs were 6319.6 cd/m2, 4.21 cd/A, and 1.03 %, respectively. The fabricated ink-jet printing QLEDs showed a luminance of 13.33%, a current efficiency of 23.8%, and a quantum efficiency of 23.62% as compared with those of the spin-coated QLEDs.