Efficient fluorescent OLEDS based on assistant acceptor modulated HLCT emissive state for enhancing singlet exciton utilization

Abstract

OLED with C6/C9 substituted phenanthroimidazoles (DDPPPA/DDPBA) show blue emission with maximum external quantum efficiency (ηex), current efficiency (ηc) and power efficiency (ηp) of 5.7/6.0%, 10.5/12.0 cd A−1 and 8.3/9.2 lm W−1, respectively.

Novel Deep‐Blue Hybridized Local and Charge‐Transfer Host Emitter for High‐Quality Fluorescence/Phosphor Hybrid Quasi‐White Organic Light‐Emitting Diode

“…Notably, the oscillator strength of the S 0 → S 1 is calculated to be as high as 2.4196, which is consistent with the value of 2.2082 derived from its relatively high molar extinction coefficients (log ε = 4.91 in dichloromethane). Such oscillator strength together with the radiative decay rate constant k r ≈ 5.6 × 10 8 s −1 in film are quite high levels in reported organic emitters, [35][36][37] indicating that high fluorescence efficiency for 2TPA-PPI can be anticipated. In contrast, the high-lying T 1 and T 2 states of 2TPA-PPI presented the LE states with the almost completely orbital overlap.…”

Non-doped OLEDs based on tetraphenylethylene phenanthroimidazoles with negligible efficiency roll-off: effects of end group regulated stimulus responsive AIE luminogens

“…Phenanthroimidazoles, TPE-NPPB and TPE-APPB are freely soluble in dichloromethane, tetrahydrofuran, chloroform and hexane but they are poorly soluble in water, alcohol and acetonitrile. The photophysical properties of TPE-NPPB and TPE-APPB were studied in tetrahydrofuran using electronic spectroscopy (Figure 3, cm -1 M -1 ), 346nm (Ɛ max -28901.73 cm -1 M -1 )] which confirm the presence of effective charge transfer transitions in these materials [31,32].…”

Doped and non-doped blue organic light-emitting diodes based on AIEgens with high exciton utilization efficiency and external quantum efficiency

“…The theoretically calculated high EQE are of 3. [15,16]. The experimental EQE > theoretical EQE because larger triplet excitons are converted to singlet excitons in EL process [15,16]…”

“…Phenanthroimidazoles with C2 substitution developed effective conjugation and results in deep blue emission, whereas N1 substitution does not affect the optical properties significantly because of perpendicular configuration [15][16][17][18][19]. Though C2 and N1 substituted 3 phenanthroimidazoles have been studied widely, C6 and C9 substituted phenanthrimidazole derivatives have not been analysed broadly [20,21].…”