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Due to the limited molecular design strategy, the development of ultrahigh color purity deep blue aggregation-induced emission (AIE) emitters with excellent photophysical and electroluminescence performances is still facing challenges at present. In this study, an effective design strategy for deep blue emitters is proposed, which can improve the performances of non-doped organic light-emitting diodes (OLEDs) by adjusting the link mode of the phenyl bridge and utilizing the steric hindrance effect of the rigid plane. Two new emitters, 3BCzPT and 4BCzPT, were obtained with phenanthroline acceptor and carbazole donor for deep blue emitting OLEDs. Particularly, 3BCzPT has been proven to have AIE characteristics through photophysical properties. Non-doped OLEDs with 3BCzPT demonstrate prominent electroluminescence (EL) performances reaching a maximum current efficiency (CEmax) of 6.3 cd A−1 and maximum external quantum efficiency (EQEmax) of 3.81%, well as ultrahigh color purity with Commission Internationale de L'Eclairage (CIE) coordinates of (0.151, 0.053). While the parameters of non-doped OLED based 4BCzPT are 4.2 cd A−1, 1.96% and (0.147, 0.082). Both emitters exhibit narrow EL spectra with the full-width at half maximum (FWHM) of 56 and 52 nm. • A strategy to construct deep blue AIE emitters with D-π-A-π-D configuration was proposed. • Highly twisted configurations are beneficial to the formation of weak intra/intermolecular interaction. • Non-doped OLEDs provided ultrapure deep blue emission with CIE x ≤0.15 and CIE y ≤0.08. • This feasible strategy can enrich the design strategy of deep blue emitters and further extend their application in OLEDs. [ABSTRACT FROM AUTHOR]

Two polymeric hosts PCzTPP and PCzTPPO with twisted geometrical configurations for blue phosphorescent polymer light-emitting diodes (PhPLEDs) were designed and synthesized by incorporating electron-accepting carbazole units with electron-donating TPP/TPPO groups. This molecular design endows PCzTPP and PCzTPPO with high glass transition temperatures of 204 °C and 215 °C, high triplet energies of 2.72 eV and bipolar features. In addition, the HOMO and LUMO of these polymers matched well with the HOMO of the hole-transport layer and the Fermi level of cathode compared with PVK, which facilitated the injection of holes and electrons. PCzTPP- and PCzTPPO-based single-emissive-layer blue PhPLEDs were fabricated with simplified device configuration by solution process using FIrpic as a dopant. These devices exhibited lower turn on voltages (<8 V) than PVK-based devices (12 V). The maximum luminances of PCzTPP- and PCzTPPO-based devices were twofold and threefold that of PVK-based devices, and the maximum current efficiencies were nearly threefold and ninefold, respectively. Moreover, PCzTPPO-based solution processed blue PhPLEDs with improved configuration showed maximum current efficiency and external quantum efficiency of 14.5 cd/A and 6.6%, respectively. [ABSTRACT FROM AUTHOR]

A novel iridium(III) complex bis(2-(naphthalen-1-yl)-6-(trifluoromethyl)benzothiazole)iridium(acetylacetonate) (CF 3 BT-N) 2 Ir(acac) with an orange–red emission was synthesized. The incorporation of CF 3 and naphthalene groups into benzimidazole to act as a new ligand causes a significant change of both HOMO and LUMO energy levels of the iridium complex compared with the yellow emissive parent compound comprising the 2-phenylbenzimidazole ligand. As a result, a bathochromic shift by as much as 50 nm of the phosphorescence emission peak can be achieved. Electronic properties of (CF 3 BT-N) 2 Ir(acac) were examined by time-dependent density functional theory (TD-DFT) calculations. The influence of such substituent groups on the photophysical, electrochemical and electroluminescent properties of iridium complex was studied. Furthermore, two- and three-element solution-processed white organic light-emitting diodes (WOLEDs) with high performance can be realized by using this kind of orange–red phosphorescent emitter in conjunction with other phosphors in a single emissive layer. A maximum luminous efficiency of 10.9 cd A −1 with CIE coordinates of (0.27, 0.37) was obtained for the two-element WOLEDs. For the three-element WOLED, a maximum luminance of 22716 cd m −1 and a maximum luminous efficiency of 14.6 cd A −1 with CIE coordinates of (0.33, 0.42) can be achieved. [ABSTRACT FROM AUTHOR]