Excellent n-type light emitters based on AIE-active silole derivatives for efficient simplified organic light-emitting diodes†
In order to fabricate high-performance, non-doped and simplified OLEDs, excellent p/n-type light emitters with both high solid-state emission efficiencies and good carrier-transporting abilities are urgently needed, especially efficient n-type light emitters. Herein, we designed and synthesized four new silole derivatives, (PBI)2DMTPS, (PBI)2MPPS, (PPI)2DMTPS, and (PPI)2MPPS, consisting of the 2,3,4,5-tetraphenylsilole unit and 1-phenyl-1H-benzo[d]imidazole (PBI) or 1-phenyl-1H-phenanthro[9,10-d]imidazole (PPI) groups. These novel siloles are aggregation-induce emission (AIE)-active and highly emissive in solid films, and show good thermal stabilities and low LUMO energy levels. It is noteworthy that the amorphous films of (PBI)2DMTPS and (PBI)2MPPS present high electron mobilities of 1.24 × 10−4 and 3.42 × 10−4 cm2 V−1 s−1, respectively, at an electric field of 5.5 × 105 V cm−1, which are superior to that of 1,3,5-tris(phenyl-2-benzimidazolyl)benzene (TPBi). The non-doped trilayer OLED of (PPI)2DMTPS exhibits an outstanding electroluminescence (EL) performance with efficiencies of 15.06 cd A−1, 16.24 lm W−1 and 4.84%. More importantly, an efficient double-layer OLED is achieved based on (PBI)2DMTPS, offering comparable EL efficiencies (13.30 cd A−1, 14.51 lm W−1 and 4.25%) with respect to those of its trilayer OLED (13.50 cd A−1, 12.58 lm W−1 and 4.22%). These results demonstrate an effective approach towards n-type light emitters for efficient, simplified and low-cost OLEDs.
- This article is part of the themed collection: Celebrating 50 years of Professor Fred Wudl’s contributions to the field of organic semiconductors