Efficient quantum-dot light-emitting diodes using ZnS–AgInS2 solid-solution quantum dots in combination with organic charge-transport materials

Colloidal quantum dots (QDs), which exhibit highly saturated color emission, are expected to be used as emitting materials in wide-color-gamut displays. However, the development of low-toxicity alternatives is necessary because QDs with high color purity and highly efficient emission contain toxic materials such as Cd and Pb. In this study, QD light-emitting diodes (QD-LEDs) with ZnS–AgInS2 solid-solution nanoparticles [(AgIn)xZn2(1−x)S2, ZAIS] as low-toxicity QDs were fabricated and their electroluminescence properties were investigated. The ZAIS QDs exhibited red photoluminescence, with a peak wavelength of ca. 700 nm. Because the charge-injection barrier of ZAIS QDs without a wide-bandgap shell is relatively low, the QD-LEDs with red ZAIS QDs in combination with organic charge-transport materials induce electron injection from an organic electron-transport layer. These QD-LEDs exhibit an external quantum efficiency of 2.2%, a turn-on voltage of 2.4 V, and red emission with chromaticity coordinates (0.66, 0.33).Colloidal quantum dots (QDs), which exhibit highly saturated color emission, are expected to be used as emitting materials in wide-color-gamut displays. However, the development of low-toxicity alternatives is necessary because QDs with high color purity and highly efficient emission contain toxic materials such as Cd and Pb. In this study, QD light-emitting diodes (QD-LEDs) with ZnS–AgInS2 solid-solution nanoparticles [(AgIn)xZn2(1−x)S2, ZAIS] as low-toxicity QDs were fabricated and their electroluminescence properties were investigated. The ZAIS QDs exhibited red photoluminescence, with a peak wavelength of ca. 700 nm. Because the charge-injection barrier of ZAIS QDs without a wide-bandgap shell is relatively low, the QD-LEDs with red ZAIS QDs in combination with organic charge-transport materials induce electron injection from an organic electron-transport layer. These QD-LEDs exhibit an external quantum efficiency of 2.2%, a turn-on voltage of 2.4 V, and red emission with chromaticity coordinates (0.6...