Efficient, deep-blue organic electrophosphorescence by guest charge trapping

Abstract

We demonstrate efficient, deep-blue organic electrophosphorescence using a charge-trapping phosphorescent guest, iridium(III) bis(4′,6′-difluorophenylpyridinato)tetrakis(1-pyrazolyl)borate (FIr6) doped in the wide-energy-gap hosts, diphenyldi(o-tolyl)silane (UGH1) and p-bis(triphenylsilyly)benzene (UGH2), where exciton formation occurs directly on the guest molecules. Charge trapping on the guest is confirmed by the dependence of the drive voltage and electroluminescence spectrum on guest concentration. Ultraviolet photoemission spectroscopy measurements establish the relative highest occupied molecular orbital positions of FIr6 in UGH1 and UGH2. Peak quantum and power efficiencies of (8.8±0.9)% and (11.0±1.1) lm/W in UGH1 and (11.6±1.2)% and (13.9±1.4) lm/W in UGH2 are obtained, while the emission in both cases is from FIr6 and is characterized by Commission Internationale de l’Eclairage coordinates of (x=0.16, y=0.26) in UGH2.

Thermally Activated Delayed Fluorescence Emitters for Deep Blue Organic Light Emitting Diodes: A Review of Recent Advances

“…Recently, Hatakeyama et al reported a new strategy to design effective deep blue triarylboron based emitters [95]. The chemical structures of boron emitters (28)(29) are given in Figure 6, while their novel design strategy is displayed in Figure 7. It is well known that efficient TADF-based OLEDs need a fluorophore with a small ∆E ST .…”

“…The authors obtained pure blue TADF molecules by using multiple resonance effect to efficiently separate HOMO-LUMO. The first molecule (28) showed in the Figure 6 comprises a triphenylboron donor fused with two triphenylamine acceptors. The second molecule (29) is designed by increasing the length of the π-conjugated system as well as the number of electron donors.…”

Synthesis and Electroluminescence of New Organic Emitters Based on a π-Conjugated 1,3,5-Triazine Core

“…[1][2][3][4] Large efforts to enable the high luminescence performance in OLEDs [5][6][7] have resulted in multilayered device architectures. On the contrary, the simple structure should have some advantages because it allows the brief fabrication of the device.…”

Intense and efficient ultraviolet electroluminescence from organic light-emitting devices with fluorinated copper phthalocyanine as hole injection layer

“…[2] In the research stream, organic semiconductors with a wide bandgap are becoming important because triplet excitons must be confined in the phosphors. In particular, wide bandgap organic semiconducting materials are attractive as blue light-emitting phosphors [3][4][5], because the well-known energy gap between the lowest triplet excited state (T 1 ) and ground state (S 0 ) of organic materials has become much smaller than that between the lowest singlet excited state (S 1 ) and S 0 . Furthermore, since wide bandgap organic semiconducting materials are potentially applicable to ultraviolet (UV: below the wavelength of 380 nm) light emission devices, surface UV light-emitting devices, which are hardly available using other light-emitting technologies, could open another application field for organic devices.…”