HLCT Driven Twisted Benzo[d]thiazole Based D-A-D Fluorophores for High-Performance, Two-Component White LEDs

Area of Science:

• Materials Science
• Organic Chemistry
• Optoelectronics

Background:

• Tailored fluorophore design is crucial for advanced optoelectronic devices like white LEDs.
• Donor-acceptor (D-A) systems offer tunable photophysical properties for light emission applications.

Purpose of the Study:

• To design, synthesize, and characterize novel benzo[d]thiazole-based donor-acceptor-donor (D-A-D) fluorophores.
• To evaluate the potential of these synthesized luminogens as phosphors for white light-emitting diodes (LEDs).

Main Methods:

• Synthesis of three D-A-D luminogens incorporating triphenylamine, diphenylamine, and carbazole donor units.
• Characterization using single-crystal X-ray diffraction, photophysical property measurements (solvatochromism, lifetime studies), and Density Functional Theory (DFT) calculations.
• Fabrication and testing of white LED devices incorporating the synthesized luminogens with a red-emitting Europium(III) phosphor.

Main Results:

• Synthesized D-A-D systems exhibited twisted molecular geometries, leading to greenish-blue emission.
• Photophysical studies indicated hybridized local and charge transfer (HLCT) character in the excited states.
• The fabricated white LED demonstrated a color rendering index (CRI) of 74, excellent chromaticity coordinates, and a high correlated color temperature (CCT) of 7207 K.
• An enhanced absolute photoluminescence quantum yield (PLQY) of 46.33% was achieved with an additional diphenylamine donor unit.

Conclusions:

• The synthesized benzo[d]thiazole-based D-A-D systems are efficient fluorophores with tunable emission properties.
• These materials show significant potential for applications in optoelectronics and next-generation lighting technologies.
• Molecular design strategies, such as incorporating specific donor units, can enhance luminescent properties for LED applications.