•A series of highly efficient deep blue emitters are designed and synthesized.•They present narrow FWHM, high quantum yields and high thermal stabilities.•The doped green device with CIE of (0.31, 0.62) and a ηc of 33 cd A−1 is obtained.•The doped white device with CIE of (0.31, 0.31) and a ηc of 5.5 cd A−1 is obtained.A series of highly efficient deep blue emitters comprising of carbazole and phenanthro[9,10-d]imidazole moieties are designed and synthesized. These compounds present deep blue emission, narrow FWHM, high quantum yields, high thermal and morphological stabilities. Among them, the design strategy of 2:1 ratio of phenanthro[9,10-d]imidazole and carbazole unit affords M2 with more balanced carrier injection and transporting properties. OLEDs using M2 as emitting layer is observed to deliver a truly deep blue CIE of y < 0.06 with a highest external quantum efficiency of 3.02%. By taking the full advantage of these deep blue emitters, they are further served as excellent hosts for fluorescent and phosphorescent dyes. High-performance green phosphorescent device based on M2/Ir(ppy)3 is attained with a maximum current efficiency of 33.35 cd A−1, a power efficiency of 22.99 lm W−1 and a maximum external quantum efficiency of 9.47%. When doped with an orange fluorescent material, upon careful tuning the doping proportion, the two-emitting-component white OLED is successfully fabricated with a maximum current efficiency of 5.53 cd A−1 and CIE coordinates of (0.313, 0.305). Both the non-doped and doped devices exhibited high operational stability with negligible efficiency roll-off over the broad current density range.

A series of new A–π–D–π–A molecules including diphenylamine and carbazole had been synthesized and characterized (T1–T3). T1 and T2 displayed aggregation-induced emission enhancement (AIEE): exhibiting weak fluorescence in pure THF, which a signification AIEE effect was observed in mixture with a water fraction (fw) of 90% with a sharp increase in fluorescence intensity. T3 displayed aggregation-caused quenching (ACQ): exhibiting strong fluorescence in pure THF, which a signification ACQ effect was observed in mixture with a water fraction (fw) of 90% with a sharp decrease in fluorescence intensity. Their two-photon absorption (2PA) had been investigated using the open-aperture Z-scan technique, and the values of the 2PA cross section at 800 nm for T1–T3 were 1115, 681, in chloroform, respectively.Three new A–π–D–π–A molecules had been synthesized and characterized (T1–T3). The 2PA cross section at 800 nm for T1–T3 were 1115, 681, 434 GM, respectively.