Near-quantitative internal quantum efficiency in a light-emitting electrochemical cell

Area of Science:

• Materials Science
• Photochemistry
• Organic Electronics

Background:

• Developing efficient light-emitting materials is crucial for advanced display and lighting technologies.
• Iridium(III) complexes are promising candidates for organic light-emitting diodes (OLEDs) due to their phosphorescent properties.

Purpose of the Study:

• To synthesize and characterize a novel green-light-emitting iridium(III) complex.
• To evaluate the performance of this complex in a simple solid-state light-emitting electrochemical cell (LEC).
• To determine the factors limiting device efficiency.

Main Methods:

• Synthesis of a specific iridium(III) complex.
• Fabrication of single-layer LEC devices using the synthesized complex in a thin-film configuration.
• Measurement of photoluminescence quantum yield (PLQY) in thin films.
• Characterization of device performance, including external quantum efficiency (EQE) and power efficiency.

Main Results:

• The synthesized iridium(III) complex exhibits a photoluminescence quantum yield close to unity in a thin-film state.
• The single-layer LEC device achieved an external quantum efficiency of approximately 15%.
• The device demonstrated a power efficiency of 38 lumens per watt (Lm/W).

Conclusions:

• High external efficiencies in these devices are attributed to near-quantitative internal electron-to-photon conversion.
• The photoluminescence quantum yield in solid films is the primary limiting factor for device efficiency.
• The demonstrated efficiencies highlight the potential of these simple electroluminescent devices for practical lighting and signage applications.