A new type of light-emitting hybrid device based on colloidal quantum dots (QDs) and an ionic transition metal complex (iTMC) light-emitting electrochemical cell (LEC) is introduced. The developed hybrid devices show light emission from both active layers, which are combined in a stacked geometry. Time-resolved photoluminescence experiments indicate that the emission is controlled by direct charge injection into both the iTMC and the QD layer. The turn-on time (time to reach 1 cd/m 2 ) at constant voltage operation is significantly reduced from 8 min in the case of the reference LEC down to subsecond in the case of the hybrid device. Furthermore, luminance and efficiency of the hybrid device are enhanced compared to reference LEC directly after device turn-on by a factor of 400 and 650, respectively. We attribute these improvements to an increased electron injection efficiency into the iTMC directly after device turn-on.

Red ionic iridium-based transition metal complex light-emitting electrochemical cells (iTMC-LECs) with emission centered at ca. 650 nm, maximum efficiency of 0.3%, maximum brightness above 650 cd m −2 , and device lifetime well above 200 and 33 h at brightness levels of 10 and 210 cd m −2 , respectively, are realized by the introduction of a p-type polymer interface to the standard design of [Ir-(ppy) 2 (pbpy)] + [PF 6 ] − (Hppy = 2-phenylpyridine, pbpy = 6-phenyl-2,2′-bipyridine) iTMC-LEC. The unexpected color shift from yellow to red is studied in detail with respect to operation conditions and material combination. The experimental data suggest that either exciplex formation or subordinate, usually suppressed optical transitions of the iTMC might become activated by the introduced interface, causing the pronounced red shift of the peak emission wavelength.

Colloidal quantum dots (QDs) are attractive candidates for future lighting technology. However, in contrast to display applications, the realization of balanced white lighting devices remains conceptually challenging. Here, we demonstrate two-component white light-emitting QD-LEDs with high color rendering indices (CRI) up to 78. The implementation of orange CuInS/ZnS (CIS/ZnS) QDs with a broad emission and high quantum yield together with blue ZnCdSe/ZnS QDs in a mixed approach allowed white light emission with low blue QD content. The devices reveal only a small color drift in a wide operation voltage range. The correlated color temperature (CCT) could be adjusted between 2200 and 7200 K (from warm white to cold white) by changing the volume ratio between orange and blue QDs (1:0.5 and 1:2).

Quantum dot/electrolyte hybrid light‐emitting devices (QLECs) present a novel class of large‐area light‐emitting devices potentially combining the efficiency, robustness, and color‐tunability of colloidal quantum dots (QDs) with the simple device architecture and easy fabrication of light emitting electrochemical cells. In this work, a Cd‐free QLEC based on CuInS2/ZnS (CIS/ZnS) core/shell QDs is presented. The impact of the amount of ionic liquid on the QLEC device performance is systematically studied. The introduction of the additional electron injecting/hole blocking ZnO nanocrystal top layer as well as the proper adjustment of the ionic component leads to CIS‐based QLECs exceeding 350 cd m−2 in brightness.

Large-area light emitters like organic (OLEDs) or quantum dot light-emitting devices (QLEDs) and light-emitting electrochemical cells (LECs) have gained increasing interest due to their cost-effective fabrication on various even flexible substrates.