Highly efficient blue organic light-emitting diodes based on carbene-metal-amides

Abstract

Carbene-metal-amide type photoemitters based on CF3-substituted carbazolate ligands show sky-blue to deep-blue photoluminescence from charge-transfer excited states. They are suitable for incorporation into organic light-emitting diodes (OLEDs) by thermal vapour deposition techniques, either embedded within a high-triplet-energy host, or used host-free. We report high-efficiency OLEDs with emission ranging from yellow to blue (Commission Internationale de l'Éclairage (CIE) coordinates from [0.35, 0.53] to [0.17, 0.17]). The latter show a peak electroluminescence external quantum efficiency (EQE) of 20.9 % in a polar host. We observe that the relative energies of CT and 3 LE states influence the performance of deep-blue emission from carbene-metal-amide materials. We report prototype host-free blue devices with peak external quantum efficiency of 17.3 %, which maintain high performance at brightness levels of 100 cd m -2 .

Simple Synthetic Routes to Carbene‐M‐Amido (M=Cu, Ag, Au) Complexes for Luminescence and Photocatalysis Applications

“…In the course of the last five years, carbene‐metal‐amido (CMA) complexes of the coinage metals have emerged as highly promising candidates for application in organic light‐emitting diodes (OLEDS) and other next‐generation photonic applications [1–14] . Some examples have already been demonstrated in highly luminescent OLEDS [4,6,7–9,11–13] .…”

“…For the latter, the most frequently encountered ones are those of the cyclic (alkyl)(amino) carbene and monoamido‐ or diamido‐carbene (MAC and DAC, respectively) families, [3–14] while examples bearing the more common (benz)imidazolylidene framework and a mesoionic carbene have been reported only very recently [19,20] . The peculiar combination of electronic properties of the single components enables the population of ligand‐to‐ligand (LL)CT states with a small energy gap between the singlet and triplet excited states, which is highly beneficial for emission via Thermally Activated Delayed Fluoresence (TADF) with extraordinarily high radiative rate constants k r [3–14,17–19,21] . However, variations of the general formula, specifically to make it more suitable for other photophysical, ‐chemical or ‐catalytic applications, has been of comparatively lower priority.…”

Bistriazoles with a Biphenyl Core Derivative as an Electron-Favorable Bipolar Host of Efficient Blue Phosphorescent Organic Light-Emitting Diodes

“… 21 − 26 Many bipolar host materials such as mCP, mCBP, mNBICz, UGH2, CbzBiz, DPEPO, and so on were reported with the high-efficiency OLEDs. 10 , 27 − 31 Specifically, most of these bipolar hosts exhibited a faster intrinsic hole mobility compared to the intrinsic electron one. When doped with emitters as the emitting layer (EML), the effective hole mobility of this mixture was routinely greater than electron one.…”

Innovation of Materials, Devices, and Functionalized Interfaces in Organic Spintronics

“…[ 1 ] The application of several physical effects in the semiconductor industry, such as giant magnetoresistance (GMR) and tunneling magnetoresistance (TMR), particularly in inorganic devices, have initiated a revolution in magnetic storage and magnetic sensors. [ 1,2 ] Meanwhile, the rapid development and excellent performance of organic materials have led to several important applications in different fields, including organic light emitting diodes (OLEDs), [ 3,4 ] organic photovoltaic devices (OPVs), [ 5,6 ] and organic field‐effect transistors (OFETs). [ 7,8 ] The idea of integrating the immense potential of spintronics and the enormous advantages of organic materials in flexible wearable devices led to the emergence of organic spintronics.…”