Facile synthesis and color conversion of Cu-doped ZnSe quantum dots in an aqueous solution

A facile growth-doping method in aqueous solution has been developed to synthesize Cu-doped ZnSe (ZnSe:Cu) QDs by using thioglycolic acid (TGA) as a stabilizer. The effects of the Cu doping concentration, reaction temperature and pH value on the synthesis of ZnSe:Cu QDs were investigated systematically. The as-synthesized ZnSe:Cu QDs with an excellent green emission still belong to a cubic zinc blende crystalline structure, and the average particle size is approximately 3.0 nm. The photoluminescent quantum yield (PLQY) is as high as 20%, and the exciton radiative lifetime is approximately 113.8 ns. Moreover, the patterned ZnSe:Cu QDs thin films have been successfully fabricated by using an inkjet printing method to verify the ability of the potential application to the color conversion. With the assistance of 5.5 pair distributed bragg reflector (DBR) structures, the color coordinate of the ZnSe:Cu QDs thin film excited by the blue LEDs is located at (0.2182, 0.4352) and the intensity of PL peak located at 513 nm reaches to be 45.1%. In addition, the PLQY of color conversion-based ZnSe:Cu QDs thin film is approximately 9.64%. Based on these results, ZnSe:Cu QDs are potentially useful for the fabrication of optoelectronic devices, especially QDs photoluminescence and electroluminescence.