Constructing deep-blue bis-tridentate Ir(iii) phosphors with fluorene-based dianionic chelates

Abstract

Novel fluorene-based bis-tridentate Ir(iii) phosphors are capable of exhibiting both improved stability and efficient deep-blue emission in solution.

High Performance NIR OLEDs with Low Efficiency Roll‐Off by Leveraging Os(II) Phosphors and Exciplex Co‐Host

“…Generally speaking, the absorption bands < 390 nm are ascribed to the ligand centered π–π* transitions, the absorptions ranging from 390–500 nm mainly originate from 1 MLCT transitions, while the lowest energy absorption bands spanning region from 500 to 575 nm and beyond, having extinction coefficient (ε) <5 × 10 3 m −1 cm −1 , are assigned to the heavy Os(II) metal atom enhanced 3 π–π* and 3 MLCT transition, respectively. Consistent with previous results, [ 46,47 ] the triazolate derivative (Isq‐2) shows a smaller extinction coefficient than that of pyrazolate derivatives (Isq‐1 and Isq‐3) in high energy absorption bands due to more favorable π–π* transition probability of the later.…”

Probing Electron Excitation Characters of Carboline-Based Bis-Tridentate Ir(III) Complexes

“…In summary, by introducing varied substituents at the 4-position of central pyridinyl fragment of dianionic chelate or on the central phenyl coordination unit of carboline-based monoanionic pincer chelate, a series of five bis-tridentate Ir(III) complexes were successfully designed and synthesized, with an isolation yield higher than 50% and absence of any isomeric product. This result is consistent with those documented in literature [ 37 , 43 ]. The addition of methoxy and dimethylamino substituents at the 4-position of central pyridinyl fragment of dianionic chelate effectively increased the electron density at the Ir(III) metal center, which increased the MLCT contribution at the excited states, and gave a structureless emission profile.…”

“…Synthesis of dianionic chelate (phyz n )H 2 ( n = 1, 2 and 3) followed the literature precedents [ 37 , 41 ]. Commercially available 2,6-dibromopyridine and self-synthesized 2,6-dibromo-4-methoxypyridine [ 36 ] and 2,6-dibromo- N , N -dimethylpyridin-4-amine [ 38 , 39 ] were employed as the respective starting materials.…”

“…All solvents were dried and degassed before used, and commercially available reagents were used without further purification. 2,6-Dibromo-4-methoxypyridine [ 36 , 37 ], 2,6-dibromo- N , N -dimethylpyridin-4-amine [ 38 , 39 ] and 6-( tert -butyl)-9H-pyrido[2,3-b]indole [ 40 ] were prepared using methods reported in literature. All reactions were conducted under N 2 atmosphere and monitored by precoated TLC plates (0.20 nm with fluorescent indicator F254).…”

Deep‐Blue OLEDs with Rec.2020 Blue Gamut Compliance and EQE Over 22% Achieved by Conformation Engineering

“…Phosphorescent and thermally activated delayed fluorescent (TADF) emitters can harvest 100% exciton and realize high‐efficiency organic light‐emitting diodes (OLEDs) in a wide color gamut. [ 1–4 ] Currently, the trend of ultrahigh‐definition displays requires OLEDs to meet the Rec.2020 (or BT.2020, the ITU‐R Recommendation BT.2020 of the International Telecommunication Union‐Radiocommunication Sector (ITU‐R)) color gamut standard. Among the three primaries (red, green, and blue), researchers devote extensive endeavors in pursuing blue emitters satisfying the Rec.2020 standard, that is, Commission Internationale de l'Éclairage (CIE) chromaticity coordinates of (0.131, 0.046), [ 5 ] as the blue primary can simultaneously widen color gamut and reduce the power consumption of the display.…”