Highly Efficient Microcavity Organic Light-Emitting Devices with Narrow-Band Pure UV Emission

Abstract

Ultraviolet organic light-emitting devices (UVOLEDs) may combine the tunability properties of organic materials through modifying the molecular structure and the advantages such as large-area, low-cost, and facile to realize high-performance UV sources. In the state-of-the-art UVOLEDs, the external quantum efficiencies (EQE) are more than 3%, but only a few have achieved pure UV emission and could not compromise the durability and irradiance at the same time. Portable compact UV sources with a narrow band made significant achievements in biomedical science and forensic appraisal. The microcavity effect is useful for achieving the desired narrow peak emission. In this study, asymmetric structural design with a specific distributed Bragg reflector (DBR) structure was employed to achieve narrow-band pure UV emission microcavity UVOLEDs (μC UVOLEDs). These μC UVOLEDs can realize tunable wavelength from 366 to 400 nm, with a full width at half maximum (FWHM) of 9.95–15.2 nm and a maximum irradiance of 2.79–5.63 mW/cm2. Also, the durability of the μC UVOLED has been considered, which presents a lifetime of 63.2 h under an irradiance of 0.016 mW/cm2. Moreover, the ability to identify 100 RMB with an efficient μC UVOLED has also been demonstrated. This investigation not only demonstrates the encouraging potential of narrow-band pure UVOLEDs but also provides a feasible strategy for the optimal design of μC UVOLEDs by utilizing the asymmetric structure.

Organic fluorophores that emit ultraviolet light in the aggregated state

“…On the other hand, dimethylated derivative of 25a , thus 25b , exhibited UV–EL with emission maxima at 378 and 392 nm with an excellent EQE of 5.4% in a multilayer device architecture of ITO/MoO 3 /TCTA/CBP/ 25b /TPBI/LiF/Al. [ 65 ] Notably, very narrowband UV emission was realized with an FWHM of 9.95 nm by fabricating microcavity OLEDs of 25b .…”

Narrow-Band Orange–Red Emission Organic Luminophore with Dominant Low-Frequency Vibronic Coupling

“…A high standard of color purity of light is required in organic light-emitting diode (OLED) display industries, demonstrated by the full width at half maximum (fwhm) of emission spectra being less than 0.14 eV. , To meet the standard, filters or optical microcavity structures are widely employed in the device architecture of the conventional OLEDs, − causing a great loss in device efficiency and energy utilization. Intrinsically, narrow-band emission materials emerged as ideal alternatives to directly provide high color purity with less intricacy for device fabrication and processing.…”

Giant Enhancement of External Quantum Efficiency in Near‐UV Organic Light‐Emitting Diodes via Device Aging and Impedance Spectroscopy Analysis

“…A UV organic light-emitting diode (UV OLED) with flexibility, low cost, and scalable manufacturing considerably broadens short-wavelength applications of an organic electronic device in exciting lighting source, chemical sensor, bioanalytical, and high-density information storage. [1][2][3][4][5][6] State-of-the-art research has mainly focused on tailoring the cathode/anode interface to achieve satisfactory carrier balance in the emissive layer, owing to the relatively wide bandgap of UV fluorescent molecules. [7,8] External quantum efficiency (EQE), the most important electro-optical parameter of UV OLEDs, has been increased from 0.1% [7] to 4.6% [8] for conventional fluorescent molecules and has recently achieved 9.3% [9] with the use of thermally activated delayed fluorescent material.…”