Electroluminescence of iridium(III) complexes containing F or CF3 substituents

Nasiri, Sohrab; Thiyagarajan, Manojkumar Dhanthala; Balijapalli, Umamahesh; Mahmoudi, Malek; Volyniuk, Dmytro; Simokaitienė, Jūratė; Pathak, Madhvesh; Iyer, Sathiyanarayanan Kulathu

doi:10.1016/j.synthmet.2020.116673

Cited by 4 publications

(2 citation statements)

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“…20,21 However, TADF emitters containing strong electron-deficient trifluoromethyl group have been rarely reported. 22,23 Molecular design of TADF compounds is performed in such a way, that their lowest excited singlet and triplet states lie very close energetically due to the spatial separation of molecular orbitals of donating and accepting moieties. 24 This can lead to the thermally activated upconversion from the latter to the former state through RISC which is actually the inverse transition processes of phosphorescence.…”

Section: Introductionmentioning

confidence: 99%

“…OLEDs based on these emitters showed improved device lifetimes and maximum EQE exceeding 21% . Variety of conjugated electron-accepting groups such cyanobenzene, triazine, oxadiazole, diphenyl sulfoxide, and so forth were used in the design of TADF emitters. , However, TADF emitters containing strong electron-deficient trifluoromethyl group have been rarely reported. , …”

Section: Introductionmentioning

confidence: 99%

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Ornamenting of Blue Thermally Activated Delayed Fluorescence Emitters by Anchor Groups for the Minimization of Solid-State Solvation and Conformation Disorder Corollaries in Non-Doped and Doped Organic Light-Emitting Diodes

Mahmoudi

Gudeika

Kutsiy

et al. 2022

ACS Appl. Mater. Interfaces

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Motivated to minimize the effects of solid-state solvation and conformation disorder on emission properties of donor–acceptor-type emitters, we developed five new asymmetric multiple donor–acceptor type derivatives of tert-butyl carbazole and trifluoromethyl benzene exploiting different electron-accepting anchoring groups. Using this design strategy, for a compound containing four di-tert-butyl carbazole units as donors as well as 5-methyl pyrimidine and trifluoromethyl acceptor moieties, small singlet-triplet splitting of ca. 0.03 eV, reverse intersystem crossing rate of 1 × 106 s–1, and high photoluminescence quantum yield of neat film of ca. 75% were achieved. This compound was also characterized by the high value of hole and electron mobilities of 8.9 × 10–4 and 5.8 × 10–4 cm2 V–1 s–1 at an electric field of 4.7 × 105 V/cm, showing relatively good hole/electron balance, respectively. Due to the lowest conformational disorder and solid-state solvation effects, this compound demonstrated very similar emission properties (emission colors) in non-doped and differently doped organic light-emitting diodes (OLEDs). The lowest conformational disorder was observed for the compound with the additional accepting moiety inducing steric hindrance, limiting donor–acceptor dihedral rotational freedom. It can be exploited in the multi-donor–acceptor approach, increasing the efficiency. Using an emitter exhibiting the minimized solid-state solvation and conformation disorder effects, the sky blue OLED with the emitting layer of this compound dispersed in host 1,3-bis(N-carbazolyl)benzene displayed an emission peak at 477 nm, high brightness over 39 000 cd/m2, and external quantum efficiency up to 15.9% along with a maximum current efficiency of 42.6 cd/A and a maximum power efficiency of 24.1 lm/W.

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