Narrowband Emission from Organic Fluorescent Emitters with Dominant Low-Frequency Vibronic Coupling

Organic fluorescent emitters with narrowband emissions are highly desirable for high-resolution organic light-emitting diode (OLED) display technology. In principle, this can be achieved by specifically controlling the intrinsic structural relaxation and vibronic coupling in the excited state. Here, a design strategy to realize narrowband emission of organic fluorescent emitters is proposed by significantly enhancing the low-frequency vibronic coupling strength (Lambda) while simultaneously reducing the high-frequency. of the commonly involved stretching modes. The quinolino-[3,2,1-de]acridine-5,9-dione (QAO) species is found to be directly associated with this design principle. By introducing single bond-linked peripheral moieties into the QAO core, the constructed QAO derivatives are shown to exhibit better performance, by achieving a full width at halfmaximum of 23 nm/0.13 eV in toluene for the narrowest band as well as 27 nm/0.15 eV in doped devices, with negligible dependence on the doping concentrations. The maximum external quantum efficiency of the fabricated blue OLED is 17.5%.

Automated summary

A design strategy to achieve narrowband emission of organic fluorescent emitters is proposed by enhancing low-frequency vibronic coupling while reducing high-frequency ones. The designed QAO derivatives exhibit better performance with narrowest band emissions in toluene and doped devices.