Red‐Green‐Blue‐Yellow (RGBY) Magnetic Circularly Polarised Luminescence (MCPL) from Optically Inactive Phosphorescent Ir(III) Complexes

Abstract

The development of phosphorescent organometallic molecules, capable of full-colour circularly polarised luminescence with a controlled polarised sign in the absence of any chiral chemical influences, presents a significant scientific and engineering challenge. The current study describes the first red-green-blueyellow (RGBY) coloured, nearly mirror-image magnetic circularly polarised luminescence (MCPL) in dimethyl sulfoxide and dichloromethane, from four optically inactive Iridium(III) complexes viz. Ir(III)(piq) 3 , Ir(III)(ppy) 3 , Ir(III)(F 2 -ppy) 2 (pic), and Ir-(III)(BT) 2 (acac), bearing achiral organic cyclometalated and ancillary ligands. The absolute value of the anisotropy factors, j g MCPL j , ranging from 0.9 × 10 À 3 to 2.5 × 10 À 3 in the presence of an external 1.6 T magnetic field was nearly identical to the enantiomerically pure Iridium (III) complexes at zero-magnetic fields. Unexpectedly, when the same north-up/south-up Faraday geometries were used, the MCPL signs were inverted due to the achiral ligands.

External Magnetic Field Driven, Ambidextrous Circularly Polarized Electroluminescence from Organic Light Emitting Diodes Containing Racemic Cyclometalated Iridium(III) Complexes

“…Thus, the MCPEL and MCPL spectral signs were influenced by the ligand environment (homoleptic or heteroleptic) in the organoiridium(III) compounds. [66] As anticipated, altering the Faraday geometry caused reversal of the MCPEL and MCPL spectral signs. In N-up geometry, a (À )-sign for Ir(III)(ppy) 3 , and (+)-sign for Ir-(III)(ppy) 2 (acac) were observed, and vice-versa in S-up geometry.…”

“…The chiroptical signs for Device‐I and Device‐II were identical to those of the corresponding MCPL in CH 2 Cl 2 solution, while using the same organoiridium(III) compound, in the same Faraday geometry. Thus, the MCPEL and MCPL spectral signs were influenced by the ligand environment (homoleptic or heteroleptic) in the organoiridium(III) compounds [66] …”

Enhancement of circularly polarized electroluminescence via reflection reversal under a magnetic field

“…In recent years, external static magnetic fields have garnered significant attention as a physical bias to induce circularly polarised signals in the photoexcited states of achiral and racemic organic, organic-inorganic, or inorganic luminescent materials. [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] In this context, we have succeeded in generating full-colour red-green-blue-yellow (RGBY) CPEL under a magnetic field from organic light-emitting diodes (OLEDs) incorporated with optically inactive phosphorescent iridium(III) luminophores in the EML. That is, the application of an external magnetic field allows us to develop phosphorescent CP-OLEDs without any chiral phosphors, namely, magnetic CP-OLED (MCP-OLEDs).…”

External magnetic field-induced circularly polarized luminescence and electroluminescence from optically inactive thermally activated delayed fluorescence material 4CzIPN

“…One solution to this challenge is to utilize the magnetic circular dichroism (MCD) theory proposed by Riehl and Richardson (Riehl and Richardson, 1977;Ghidinelli et al, 2021) to induce CPL because MCPL can be viewed as the reverse process of MCD. According to this theory, as a versatile physical bias, external static magnetic fields can induce chiral spectral signals from both ground and photoexcited states in many achiral and racemic optically inactive organic, organometallic, and inorganic luminescent materials (Rikken and Raupach, 1997;Valiev et al, 2014;Knowles et al, 2015;Wu et al, 2017;Ivchenko, 2018;Ghidinelli et al, 2020;Imai, 2020;Imai, 2021;Kitahara et al, 2021;Zhang et al, 2021;Hara et al, 2022).…”