Chromaticity Control in Light‐Emitting Electrochemical Cells via Thermally Activated Emission in Assemblies of a BN‐Doped Pyrenyl Hydrocarbon

This work outlines the synthesis and photo-/electro-luminescent behavior of a new C-shaped BN-doped benzenoid hydrocarbon using N-directed borylation in a unique lattice-embedded graphitic C2–B–N motif at the pyrene K-region. This BN-doped polycyclic aromatic hydrocarbon (PAH) exhibits a green fluorescent emission in solution with a photoluminescent quantum yield of 91%. In contrast, thin-films applied to light-emitting electrochemical cells (LECs) feature a temperature-dependent dual-emission, including a broad yellowish band and a well-structured near-infrared band that are barely met in the prior art. What is more striking, this temperature-dependent dual-emission can be easily controlled in LECs with the driving conditions, realizing green-yellow (x/y CIE color coordinates of 0.36/0.61; stabilities of 200 h; efficiency of 0.30 lm W−1) and yellow-orange (x/y CIE color coordinates of 0.50/0.49; stabilities of ≈70 h; efficiency of 0.26 lm W−1) devices. Finally, the expected greenish devices (x/y CIE color coordinates of 0.30/0.62; stabilities of 0.3 h; efficiency of 0.46 lm W−1) can be fabricated using a host:guest active layer that disrupts the formation of the thermally activated emissive assemblies. Hence, this work highlights the films' thermally activated emission behavior to control device chromaticity using this BN-doped PAH.