Tailoring balance of carrier mobilities in solid-state light-emitting electrochemical cells by doping a carrier trapper to enhance device efficiencies

Luminescent Ionic Transition‐Metal Complexes for Light‐Emitting Electrochemical Cells

“…This LEC exhibited a 1.4-times higher efficiency than the pristine device leading to an EQE of 12.75 % and a power efficiency of 28.7 lm W À1 . [201] 4.4.4.5. White LECs Su et al [25,159] reported the first white LEC based on the host-guest strategy (see Section 3 and 4.4.3.2).…”

Quantum Dot/Light-Emitting Electrochemical Cell Hybrid Device and Mechanism of Its Operation

“…Additionally, both light intensity and EQE are significantly enhanced for the hybrid device as compared to the LEC reference, especially directly after device turn-on (see Figure 5, panels b and c). Since electrons are believed to be the minority charge carriers in iTMC-LECs, 29,60 and particularly in the case of the selected iTMC-emitter, 61 an increase of light intensity by several orders of magnitude in the range of 0−5 min should be attributed to an improved electron injection. The positions of HOMO and LUMO levels of the iTMC, as shown in Figure 1c, support the assumption of improved electron injection by the QD layer into the iTMC layer.…”

“…1,31,32 Especially high brightness and long operation lifetime seem to be hard to unite: most devices with high brightness are short-lived and vice versa. 16,27,29 On the other hand, the discovery of stable, yellow iTMC-complex due to intramolecular π−π stacking interactions 33 and pulsed operation mode yielded devices with lifetimes exceeding 4000 h at maximum luminance over 650 cd/m 2 and subsecond turn-on times. 17 Recently, the approach of multiple π-stacking interactions yielded promising results also for red-emitting complexes, 18 making the iTMC-LECs together with their simple architecture very attractive for industrial roll-to-roll fabrication.…”

“…10,20−23 Nevertheless, the turn-on time of the iTMC-LEC can be significantly reduced by the addition of an ionic liquid to the active layer, 24,25 as well as by implementing a current driving mode of the device. 26 Despite the potential benefits of the iTMC-LECs as well as recent advances, 1 the market entry of these types of devices is challenging mainly due to the lack of at the same time efficient, bright, and long-term stable emitter materials of different colors, particularly of red 27,28 and blue 29,30 emitters, resulting in challenges in the realization of white emission. 1,31,32 Especially high brightness and long operation lifetime seem to be hard to unite: most devices with high brightness are short-lived and vice versa.…”

Luminescent Iridium Complexes Used in Light-Emitting Electrochemical Cells (LEECs)

“…For example, it was shown that by doping small amounts (up to 1.0 wt %) of a pure organic NIR emitting laser dye, 3,3 0 -diethyl-2,2 0 -oxathiacarbocyanine iodide, DOTCI, (Fig. 6) into the emissive layer of complex 4, higher device efficiencies could be obtained (EQE = 12.8 % for 0.01 wt % DOTCI) than without any dopant (EQE = 9.06 % for the pristine device DOTCI) [57]. The intrinsic hole transporting properties of 4 leads to the formation of the charge recombination zone near the cathode, which facilitates exciton quenching.…”