Novel Red‐Emitting Copper(I) Complexes with Pyrazine and Pyrimidinyl Ancillary Ligands for White Light‐Emitting Electrochemical Cells

Abstract

The synthesis, photophysical/electrochemical characterization, and implementation in light‐emitting electrochemical cells (LECs) of three novel red‐emitting heteroleptic [Cu(N^N)(P^P)]PF6 complexes are reported. The complex design consists in combining i) the bridged di(pyrazin‐2‐yl)sulfane N^N ligand with expanded π‐conjugation and electro‐withdrawing 4‐(trifluoromethyl)pyrimidine moieties and ii) the [(diphenylphosphino)phenyl] ether (DPEphos) P^P ligand. The effect of the N^N ligand substitution on the photophysical, electrochemical, ion conductivity, and morphological features in their respective powders and thin films is thoughtfully rationalized. This is rounded by the trends noted in single‐layered red‐emitting LECs (λmax = 630–660 nm) featuring moderate performances with irradiances of around 60–90 µW cm−2 and total emitted energies in the range of 4–12 mJ. A further optimization using a multilayered architecture, in which hole injection/transport and exciton formation processes are decoupled, leads to a significant enhancement of the irradiance up to ≈150 µW cm−2 and total emitted energies of 91 mJ without affecting device chromaticity. Finally, the best red‐emitting complex in LECs is used to fabricate host:guest white devices, achieving luminances of 12 cd m−2 in concert with an excellent white color quality (x/y CIE color coordinates of 0.31/0.32; color rendering index of 90) stable over lifespan.

Deep-red and near-infrared light-emitting electrochemical cells employing perovskite color conversion layers with EQE >10%

“…Even in the neat-film state, the PLQYs of the CCLs A , B , and C reach 26, 24, and 20%, respectively. These values are higher than many previously reported PLQYs of deep-red and NIR iTMCs, 29,30,33,52–57 polymers, 20–23 and small molecules 58 for LECs. As such, when these perovskite CCLs are combined with high-efficiency blue-green LECs based on complex 1 , efficient down-converted deep-red and NIR output emission can be expected.…”

“…All bluegreen LECs on diffusive substrates integrated with perovskite CCLs showed peak EQEs higher than 10%, which are among the highest reported values for the deep-red and NIR LECs based on any types of emissive materials. [15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][52][53][54][55][56][57][58]61 Making use of inorganic perovskite CCLs successfully overcomes the difficulties of moderate emission efficiencies of longwavelength organic emissive materials due to the energy-gap law. Energy down-conversion via red CCLs has been This journal is © The Royal Society of Chemistry 2022 demonstrated to realize highly efficient white LECs.…”

Versatile Biogenic Electrolytes for Highly Performing and Self‐Stable Light‐Emitting Electrochemical Cells

“…Thus, the transition toward eco-friendly LECs is becoming urgent to set in its market niche in the short term. [7] In this context, huge efforts have been carried out to introduce ecological emitters in LECs (iTMCs, [8,9] small molecules, [10,11] carbon dots, [12] etc. ), while little consideration has been placed on green ionic electrolytes.…”

Deep-red light-emitting electrochemical cells based on phosphor-sensitized thermally activated delayed fluorescence

“…21–28 However, the reported long-wavelength, i.e. , deep-red and near-infrared (NIR) LECs, which have great potential applications in bio-imaging, telecommunication, night-vision displays, and chemical sensing, commonly showed low device efficiencies, 29–61 hindering their commercialization. In these reported studies, deep-red LECs based on phosphor-sensitized fluorescence 29,30 outperform other types of deep-red LECs, i.e.…”