A single emitting layer white OLED based on exciplex interface emission

Abstract

A new triaryl molecule based on a benzene–benzothiadiazole–benzene core has been applied in a WOLED device. This very simple molecule emits from a combination of emissive states (exciton/electromer/exciplex/electroplex) to give white light with CIE coordinates of (0.38, 0.45) and a colour temperature of 4500 K

Solution‐Processable Thermally Activated Delayed Fluorescence White OLEDs Based on Dual‐Emission Polymers with Tunable Emission Colors and Aggregation‐Enhanced Emission Properties

“…Therefore, we tentatively assign the 580 nm peak in EL to the effect of the electric field on the randomly oriented dipole moments of the TADF units, i.e., electroplex emission, or most probably due to the formation of an electromer, which cannot be observed in PL spectra. The formation of an electromeric state is observed usually when trapped carriers recombine under the interaction with an electric field, and cause the emission to red‐shift with respect to photoluminescence Therefore, the white emission of the device originates from the combination of the CT and electromer emission. However, further studies are need to fully understand this effect in our materials .…”

Realizing 20% External Quantum Efficiency in Electroluminescence with Efficient Thermally Activated Delayed Fluorescence from an Exciplex

“…The reason for the relatively lower efficiency of device G2, when compared with device G1 could be due to the formation of an electromer, due to the presence of defect sites in TCBPA that may act as deep electron traps. 55,56 Therefore, when using TCBPA as HTL, OLEDs should be carefully designed to avoid emission from electromers, by shifting the emission region far enough from TCBPA. However, both G1 and G2 OLEDs exhibit low turn-on devices show η L of 2.2 cd A -1 , η P of 1.9 lm W -1 , η ext of 1.3% for NPB:PO-T2T, and η L of 5.3 cd A -1 , η P of 3.9 lm W -1 , η ext of 2.4% for TPD:PO-T2T.…”

Triphenylamine disubstituted naphthalene diimide: elucidation of excited states involved in TADF and application in near-infrared organic light emitting diodes

“…The design of TADF materials that cater towards specific OLED device manufacture requires the critical arrangement of the local triplet ( 3 LE) and charge-transfer states ( 1 CT and 3 CT) to promote the spin-vibronic coupling that underpins rISC and TADF. [30][31][32] This mechanism involves vibronic coupling between the 3 LE and 3 CT that then mediates the rISC mechanism in the CT manifold. It has become common knowledge that the arrangement and reduction, creating a small ΔES-T gap, is crucial to the efficiency of this process.…”