Effect of cathodes on high efficiency inorganic–organic hybrid LEDs based on CdSe/ZnS quantum dots

Inorganic–organic hybrid light emitting devices (HLEDs) with CdSe/ZnS quantum dot (QD) emitting layers are fabricated, and the variation of their operation characteristics with respect to a cathode material selection among Au, Al, and LiF/Al is investigated. All three types of QD-based HLEDs show orange-color emission, centered at 580 nm with a full-width at half-maximum of 50 nm, regardless of cathode material. However, quantitatively, the QD-HLED with a LiF/Al-cathode shows much larger current density and luminance compared to the other QD-HLEDs, owing to better electron injection. Moreover, the respective maximum values of power efficiency and luminous yield of the LiF/Al-cathode HLED are as large as 1.27 lm/W and 2.42 cd/A.