INVESTIGATION OF MECHANOCHROMIC AND TRIBOLOGICAL PROPERTIES OF A NOVEL THERMALLY ACTIVATED DELAYED FLUORESCENCE CARBAZOLE DERIVATIVE FOR LIGHT-EMITTING ELECTROCHEMICAL CELL APPLICATION

Abstract

This study investigates the design and synthesis of fish-shaped structures based on carbazole derivative for applications in light-emitting electrochemical cells (LEECs). A thermally activated delayed fluorescence (TADF) carbazole derivative was synthesized as an emitter in the active layer using a coupling reaction technique. [Ir(buoppy)₂(dmapzpy)]PF₆ was employed as a promising host, resulting in high-performance LEECs with enhanced brightness of 4952 cd.m^-2 and an external quantum efficiency (EQE) of 4.09%. The synthesized dye exhibited a lower singlet-triplet energy splitting (ΔE_ST) value of 0.06 eV compared to other reported counterparts, with reverse intersystem crossing (RISC) dominating its photophysical behavior. The crystalline dye demonstrated mechanochromic behavior, as its photoluminescence (PL) spectrum red-shifted upon mechanical stimulation. This mechanochromic behavior was also observed in the fabricated LEECs, and the tribological properties were further investigated.