Syntheses and Properties of Ionic Iridium Complexes and Their Applications in Solid-State Light-Emitting Electrochemical Cells
Date Issued
2010
Date
2010
Author(s)
Chen, Hsiao-Fan
Abstract
LECs (light-emitting electrochemical cells) possess several advantages over conventional OLEDs (organic light-emitting diodes) such as compatibility with air-stable electrodes (e.g., Ag and Au) and single emissive layer which can be easily conducted from cost-effective solution process. The turn-on voltages of LEC devices are generally low and approximately equal to the measured optical band gaps of the emissive materials (close to Eg /e). The low operating voltages are beneficial for the device lifetimes and power efficiencies.
In this thesis, cost-effective LEC devices based on ionic iridium complexes or ionic organic compounds have been demonstrated. The design and synthesis of various functional iridium-based complexes for the use in LEC devices including white LEC, saturated deep blue LEC, fast-response LEC, and LEC based on anionic iridium complexes were systematically performed. The results of the corresponding LEC devices are in good accordance with the expected outcome. In addition, three new Ir-based materials called “soft salt” were synthesized through metathesis reaction between halide and alkali metal salts of two cationic and three anionic iridium complexes, respectively. Since the net charge of the soft salts are zero, their use in light-emitting devices were conducted in OLED instead of LEC. The study suggests that the internal energy alignment between the two ions in the soft salts is responsible for the widely disparate results.
Subjects
OLED
LEC
Soft salt
iridium complex
fluorene
diazafluorene
ionic compound
Type
thesis
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