Warm White Light-Emitting Diodes Based on a Novel Orange Cationic Iridium(III) Complex

Area of Science:

• Materials Science
• Photochemistry
• Solid-State Lighting

Background:

• Developing efficient and stable phosphors is crucial for advanced light-emitting diode (LED) technologies.
• Iridium(III) complexes are widely investigated for their photoluminescent properties and applications in lighting.

Purpose of the Study:

• To synthesize and characterize a novel orange cationic iridium(III) complex, [(TPTA)₂Ir(dPPOA)]PF₆.
• To evaluate the potential of this complex as a phosphor for fabricating tunable white LEDs.

Main Methods:

• Synthesis of the iridium(III) complex [(TPTA)₂Ir(dPPOA)]PF₆.
• Fabrication of orange and white LEDs using the synthesized complex as a phosphor with a blue gallium nitride (GaN) chip.
• Characterization of LED performance, including Commission Internationale de I'Eclairage (CIE) values, color rendering index (CRI), correlated color temperature (CCT), and luminous efficiency (η).

Main Results:

• The synthesized complex [(TPTA)₂Ir(dPPOA)]PF₆ exhibits high thermal stability (Td = 375 °C) and good emission intensity retention at elevated temperatures.
• An orange LED was successfully fabricated using the complex as a phosphor.
• White LEDs were tuned from cold to neutral and warm white by incorporating the iridium(III) complex with a yellow Y₃Al₅O₁₂:Ce³⁺ (YAG:Ce) phosphor, demonstrating adjustable color properties and improved CRI.

Conclusions:

• The novel iridium(III) complex [(TPTA)₂Ir(dPPOA)]PF₆ is a promising candidate for developing high-performance warm white LEDs.
• The ability to tune the white light emission by adjusting the concentration of the iridium complex highlights its versatility in solid-state lighting applications.