Spin-Enhanced Reverse Intersystem Crossing and Electroluminescence in Copper Acetate-Doped Thermally Activated Delayed Fluorescence Material

Abstract

Thermally activated delayed fluorescence (TADF) materials are attractive for next-generation organic light-emitting diodes (OLEDs) because of their utilization of nonradiative triplets via reverse intersystem crossing (RISC), which requires not only a small singlet–triplet energy splitting but also the conservation of spin angular momentum. Here we use copper acetate as a spin sensitizer to facilitate RISC and thus enhance electroluminescence in TADF-exciplex OLEDs. Copper acetate is involved in the radiative decay process due to its coordination interaction with exciplex molecules having intermolecular charge-transfer characteristics, which causes significant changes in the photoluminescence intensity and lifetime. Meanwhile, magneto-photoluminescence reveals that the addition of copper acetate promotes spin conversion in the RISC process. It allows the enhancement of the electroluminescence (∼80%) from spin-sensitized OLEDs, accompanied by the suppression of magneto-electroluminescence upon the doping of copper acetate. These results illustrate that using a spin sensitizer may overcome the limitation of harvesting nonradiative triplets in organic luminescent materials and devices.

Mushroom tyrosinase enzyme catalysis: synthesis of larvicidal active geranylacetone derivatives against Culex quinquesfasciatus and molecular docking studies

“…Second, the basis for Schiff could create an intermediary with the complex of the tyrosinase residue. Materials with copper content, such as copper triflate ( Chan et al, 2017 ), copper acetate ( Jin et al, 2022 ), copper bromide ( Javaid et al, 2022 ), and copper nanoparticles ( Ouygang et al, 2022 ), are essential for Mannich base reactions. Many enzymes, including trypsin ( Momeni et al, 2022 ), lipase ( Shomal et al, 2022 ), and proteases ( Heng et al, 2022 ), catalyse the one-pot multicomponent Mannich process.…”

Giant magneto-photoluminescence at ultralow field in organic microcrystal arrays for on-chip optical magnetometer

“…After that, a series of magneto-optical effects, such as magnetic circular dichroism and magneto-chiral dichroism, have been found 3 – 9 and used for light modulation with magnetic field 10 – 14 and/or optical magnetometry 15 – 18 . A distinct type of magneto-optical effects concerning the excited state in organic materials, such as magneto-photoluminescence (MPL) 19 – 31 and magneto-electroluminescence 30 – 37 , has attracted considerable attention in past decades. It refers to the change of luminescence intensity based on the spin conversion between singlet and triplet excited states, which is useful for both studying spin-related phenomena in existing optoelectronic devices 27 – 29 , 32 – 36 and exploring intriguing device architectures for opto-spintronics applications 14 , 15 , 38 .…”

“…Phosphorescent emitters (mainly heavy metal-organic complexes), in which triplet excitons are efficiently photo-generated through the singlet-to-triplet intersystem crossing due to strong spin-orbit coupling 20 , remain insensitive to the magnetic field due to the lack of reversibility in spin conversion processes. Intermolecular charge transfer exciplexes can minimize the spin exchange energy between singlet and triplet, Δ E ST , and thus allow for both intersystem crossing and reverse intersystem crossing; thereby, the MPL magnitude increases to the level of ~5% 21 , 27 , 30 , but is still far below the corresponding magneto-electroluminescence magnitude (>30%) 35 – 37 . In addition to the intersystem crossing and reverse intersystem crossing spin conversion, singlet fission (SF) and triplet fusion (TF) processes (between one singlet and two triplets) provide a promising way to realize the spin conversion by involving two adjacent molecules and consequently enhanced MPL 13 – 15 , 23 – 26 , 28 , 42 – 44 .…”

Two‐Photon Excited Magneto‐Photoluminescence in Exciplex Material for 3D Mapping of Magnetic Field

“…[22][23][24] In these exciplex materials, the delocalization of excitons can also reduce the energy splitting between singlet and triplet states (ΔE ST ), thereby promoting the spin conversion process of intersystem crossing (ISC) and reverse intersystem crossing (RISC). [25][26][27][28][29] This significantly enhances spin-related phenomena such as magnetoresistance, magneto-photocurrent, and magneto-electroluminescence. [30][31][32][33][34][35][36][37][38][39] For instance, recent studies indicate that magneto-photoluminescence (MPL) magnitude can be elevated to the level of ≈5% in the exciplex with optimized charge separation.…”