Helically Chiral Tetradentate Pt(II) Emitters via Efficient Diastereoselective Synthesis for High-Performance Deep-Blue CP-PhOLEDs.

Highly efficient circularly polarized phosphorescent organic light-emitting diodes (CP-PhOLEDs) with narrowband deep-blue emission remain a formidable challenge, owing to the difficult chiral HPLC resolution, poor stability, low color purity, and limited brightness of chiral phosphorescent emitters. Herein, we report a novel central chirality adaptively induced helical chirality (CAIH) strategy for the diastereoselective synthesis of helically chiral tetradentate Pt(II) emitters. By introducing inexpensive and optically pure R-/S-amino alcohol-derived centrally chiral units into a rigid N-heterocyclic carbene (NHC)-based ligand, and using a diisopropylphenyl group to suppress intermolecular interactions, two pairs of emitters (M-/P-PtCP1 and M-/P-PtCP2) were obtained on a gram scale. These diastereomers exhibit excellent CP luminescence properties with dissymmetry factor (|gPL|= 10-3), ultrapure deep-blue emissions (λPL/FWHM ≈ 456/20 nm), photoluminescence quantum efficiency (ΦPL) values up to 99%, and high configurational stability. The M-/P-PtCP1- and M-/P-PtCP2-based devices also display distinct mirror-symmetric CPEL signals with |gEL| values of 10-4. Impressively, the P-PtCP1-based device simultaneously achieves record-high external quantum efficiency (EQE = 18.3% at 1000 cd m-2) and maximum brightness (Lmax = 19933 cd m-2) values among reported CP-OLEDs with CIEy < 0.12. This study provides valuable insight and new perspectives on the construction of stable helically chiral tetradentate Pt(II) emitters for high-performance CP-PhOLEDs.