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چکیده
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In this article, we explain that, how pyridine moiety increases the electroluminescence metrics including the stability of current and luminance characteristics over time in light-emitting electrochemical cell (LEC) in respect to non-pyridine ruthenium phenanthroimidazole complexes, indicating a significant enhancement of lifetime (t1/2) from 629 s to 1796 s in the range of 1800 s. When the ancillary ligand in ruthenium pyridine- phenanthroimidazole family alters from bipyridine (Bn1) to dimethyl bipyridine (Bn2), just 1% of current density loses in the same period. In particular, Bn1 shown two electroluminescence emission peaks at 614 nm and 695 nm, while non-pyridine phenanthroimidazole complex indicated an electroluminescence emission at 635 nm. To explore the role of pyridine group to increase the electroluminescence properties, we proposed that an adduction between pyridinium (pyH+) and counter ion of ClO4- (pyH+: ClO4-) in the inner coordination sphere occurred in Bn1 which subsequently leads to increase the number of charges and enhancing the charge mobility between two electrodes. On the basis of the obtained outstanding electroluminescence results, the main idea is to inspire readers to explore new avenues in the design of new emitters for OLEDs based on different ancillary ligand substitution.
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