Excimer or aggregate? Near infrared electro- and photoluminescence from multimolecular excited states of N^C^N-coordinated platinum(<scp>ii</scp>) complexes

Pander, Piotr; Sil, Amit; Salthouse, Rebecca J.; Harris, Christopher; Walden, Melissa T.; Yufit, Dimitrii S.; Williams, J. A. Gareth; Dias, Fernando B.

doi:10.1039/d2tc01511k

Cited by 27 publications

(59 citation statements)

References 62 publications

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“…Figure 1. Structures of the complexes 2, 3, 5, and 6 prepared and studied in this work,together with those of the recently reported parent complexes 1 and 4 with X = Cl 36. …”

mentioning

confidence: 78%

“…This behaviour is consistent with that reported earlier by us for complexes 1 and 4. 36 Device 4 featuring complex 3 in the EML displays an approximately four-fold increase in EQE with respect to its parent complex 1, despite a similar λEL. We attribute that to the beneficial role of the heavier halogen in potentially suppressing molecular vibrations in the aggregates, hence slowing down non-radiative decay.…”

Section: Electroluminescencementioning

confidence: 94%

“…For 2 and 5, species comprising up to five molecular units (pentamers) have been studied; for 3 and 6, the largest species studied comprise two or three units respectively. The methodology described earlier is used, 36 whereby the triplet excited state geometry of the aggregate is first obtained with TD-DFT using Orca [40][41][42] software and BP86 43 /def2-SVP, 44 and the single-point energy calculation is then undertaken using B3LYP 45,46 /def2-SVP. An anti (head-to-tail) configuration of the neighbouring units is adopted for the model, as this revealed a rather better correlation with experiment than syn orientation in earlier studies.…”

Section: Calculationsmentioning

confidence: 99%

“…All four of the investigated complexes (2, 3, 5, and 6) display strong NIR luminescence in films and thus were used as the emissive layer (EML) in OLEDs. In order to facilitate comparison with complexes 1 and 4 studied previously, 36 The OLED devices present remarkable NIR performance and they benefit from using a very thin layer of the platinum(II) complex, leading to significant reduction in the consumption of the precious metal compound. Moreover, the device performance is generally seen to be similar or even better for x = 1 or 2 nm than for x = 10 nm.…”

Section: Electroluminescencementioning

confidence: 99%

“…This study follows on from recent work in which we investigated the aggregation of complexes 1 and 4, and the use of very thin layers of these materials to generate NIR OLEDs. 36 The selection of complexes 1 and 4 in that work was made on the basis that the electron-withdrawing nature of the CF3 groups in 1, and the electron-deficient nature of the pyrimidine rings in 4, leads to stabilisation of the LUMO and a shift in the emission towards the red/NIR. In the present work, we show that the corresponding X = I derivatives (3 and 6) display a four-fold increase in NIR OLED EQE and film PLQY, while maintaining a similar λEL of 740 nm.…”

Section: Introductionmentioning

confidence: 99%

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Near-Infrared Electroluminescence beyond 940 nm in Pt(N^C^N)X Complexes: Influencing Aggregation with the Ancillary Ligand X

Salthouse

Pander

Yufit

et al. 2022

Preprint

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We present a study of aggregate excited states formed by complexes of the type Pt(N^C^N)X, where N^C^N represents a tridentate cyclometallating ligand, and X = SCN or I. These materials display near-infrared (NIR) photoluminescence in film and electroluminescence in NIR OLEDs with λELmax = 720-944 nm. We demonstrate that the two monodentate ligands X employed modulate aggregate formation compared to the parent complexes where X = Cl. While the identity of the monodentate ligand affects the energy of Pt–Pt excimers in solution in only a subtle way, it strongly influences aggregation in film. Detailed calculations on aggregates of different sizes support the experimental conclusions from steady-state and time-resolved luminescence studies at variable temperatures. The use of X = I appears to limit aggregation to the formation of dimers, while X = SCN promotes the formation of larger aggregates, such as tetramers and pentamers, leading in turn to NIR photo- and electroluminescence > 850 nm. A possible explanation for the contrasting influence of the monodentate ligands is the lesser steric hindrance associated with the SCN group compared to the bulkier I ligand. By exploiting the propensity of the SCN complexes to form extended aggregates, we have prepared an NIR-emitting OLED that shows very long-wavelength electroluminescence, with λEL(max) = 944 nm and a maximum EQE = 0.3 ± 0.1 %. Such data appear to be unprecedented for a device relying on a Pt(II) complex aggregate as the emitter.

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“…Figure 1. Structures of the complexes 2, 3, 5, and 6 prepared and studied in this work,together with those of the recently reported parent complexes 1 and 4 with X = Cl 36. …”

mentioning

confidence: 78%

Section: Electroluminescencementioning

confidence: 94%

Section: Calculationsmentioning

confidence: 99%

Section: Electroluminescencementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Near-Infrared Electroluminescence beyond 940 nm in Pt(N^C^N)X Complexes: Influencing Aggregation with the Ancillary Ligand X

Salthouse

Pander

Yufit

et al. 2022

Preprint

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Red and Near Infrared Emissive Bis‐Tridentate Ir(III) Phosphors for Organic Light Emitting Diodes

Yan,

Song,

Zhou

et al. 2023

Advanced Optical Materials

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Efficient saturated red and near‐infrared (NIR) emissive materials are needed in the development of organic light‐emitting diodes (OLEDs), with applications extending beyond flat panel displays and lighting luminaries. Toward this aim, a series of bis‐tridentate Ir(III) complexes (3a ‒ 3c and 4a ‒ 4c) are designed and synthesized, showing emission spanning the region of 601‒694 nm in degassed toluene. Their emission tuning is mainly achieved using monoanionic chromophoric chelates, L1H for red and L2H for deep‐red and NIR, where the extended π‐conjugation and electron deficient N atoms are introduced synergistically. Moreover, three ancillary chelates, X1H2, X2H2, and X3H2, delivered a secondary influence via varied donor strength to the central Ir(III) atom. The resulting red and deep‐red OLED devices exhibit maximum (max.) external quantum efficiencies (EQEs) of 21.4% and 18.1% with peak maximum at 620 and 666 nm, respectively. More impressively, the device based on 4b delivers a NIR emission peak maximum at 702 nm with a maximum EQE of 10.0%.

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Effects of Deuterium Isotopes on Pt(II) Complexes and Their Impact on Organic NIR Emitters

Wang,

Zhou,

Kuo

et al. 2024

Angewandte Chemie

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Insight into effect of deuterium isotopes on organic near‐IR (NIR) emitters was explored by the use of self‐assembled Pt(II) complexes H‐3‐f and HPh‐3‐f, and their deuterated analogues D‐3‐f and DPh‐3‐f, respectively (Scheme 2). In vacuum deposited thin film, albeit having nearly identical emission spectral feature maximized at ~810 nm, H‐3‐f and D‐3‐f exhibit remarkable difference in photoluminescence quantum yield (PLQY) of 29% and 50%, respectively. Distinction in PLQY is also observed for HPh‐3‐f (800 nm, 50%) and DPh‐3‐f (798 nm, 67%). We then elucidated the theoretical differences in the impact on near‐infrared (NIR) luminescence between Pt(II) complexes and organic small molecules upon deuteration. The results establish a general guideline for the deuteration on NIR emission efficiency. From a perspective of practical application, NIR OLEDs based on D‐3‐f and DPh‐3‐f emitters attain EQEmax of 15.5% (radiance 31,287 mW Sr‐1 m‐2) and 16.6% (radiance of 32,279 mW Sr‐1 m‐2) at 764 nm and 796 nm, respectively, both of which set new records for NIR OLEDs of > 750 nm.

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Excimer or aggregate? Near infrared electro- and photoluminescence from multimolecular excited states of N^C^N-coordinated platinum(ii) complexes

Abstract: We present an experimental and theoretical study of aggregate excited states formed by complexes of the type Pt(N^C^N)Cl, which display near-infrared (NIR) photoluminescence in film and NIR electroluminescence in OLED...

Cited by 27 publications

References 62 publications

Near-Infrared Electroluminescence beyond 940 nm in Pt(N^C^N)X Complexes: Influencing Aggregation with the Ancillary Ligand X

Near-Infrared Electroluminescence beyond 940 nm in Pt(N^C^N)X Complexes: Influencing Aggregation with the Ancillary Ligand X

Red and Near Infrared Emissive Bis‐Tridentate Ir(III) Phosphors for Organic Light Emitting Diodes

Effects of Deuterium Isotopes on Pt(II) Complexes and Their Impact on Organic NIR Emitters

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