Bi-molecular emissive excited states in platinum (II) complexes for high-performance organic light-emitting diodes

Kalinowski, J.; Cocchi, M.; Murphy, Lisa; Williams, J. A. Gareth; Fattori, V.

doi:10.1016/j.chemphys.2010.09.014

Cited by 57 publications

(48 citation statements)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This provides a reasonable explanation on the negative solvatochromism that was observed experimentally. [17] In conclusion, we report for the first time a quantitative mechanism of the photophyscis and tunable emission for the single-dopant WOLED of Pt-4 based on accurate CASSCF/ CASPT2 calculations and a comprehensive theoretical model of nonadiabatic transition/energy transfer. The two MLCT states, S MLCTy and T MLCTx , orienting along the directions of y and x in the molecular plane, respectively, were found to dominate the monomer-like blue emission.…”

Section: à07mentioning

confidence: 98%

See 1 more Smart Citation

Energy Transfer Tunes Phosphorescent Color of Single‐Dopant White OLEDs

Han

Chen

Shen

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

The photochemistry of transition-metal complexes has attracted considerable attention owing to its potential application in phosphorescent organic light-emitting diodes (OLEDs). [1][2][3][4][5][6][7][8][9][10][11][12][13] The electrophosphoresce of some Ir III and Pt II based OLEDs, which exhibit strong spin-orbit couplings, can utilize all of the electro-generated singlet and triplet excitons and achieve nearly 100 % internal quantum efficiency. [1, 2] Apart from the transition-metal centers, chelating ligands also play an important role in improving the phosphorescent efficiency.[3] The aromatic cyclometalates can form stronger bonding interactions with the transition-metal centers than other simpler organic ligands do. This may produce an array of photophysical responses, which can be used to fine tune absorption/emission spectra, excited state lifetimes, emission quantum yields, and transient absorption properties.[4] As a promising class of chelating ligands, N^C^N and C^N chelates not only make the Pt II complexes highly robust but also significantly reduce the interference of the nonradiative, metal-centered d-d transition by increasing its energy gap with respect to the ground state. [4c, 5] Figure 1 shows a few such structures of the PtL n Cl complexes that may be used as single-dopant white OLEDs (WOLEDs). Comparing with the separated multiemitters, [6] single-dopant white light emanation is underlain by the simultaneous emission from the monomer in blue and the excimer in red or orange. [7][8][9][10][11][12] As one of the promising examples, Jabbour and co-workers reported a novel Pt complex [(1,3-difluoro-4,6-di(2-pyridinyl) benzene) platinum chloride](Pt-4, see Figure 1) that shows a peak external quantum efficiency (EQE) of 16 % for the blue OLED and 9.3 % for the single-dopant WOLED, respectively.[12] They attributed its high quantum yield and narrow emission spectra to a strong mixing of the singlet metal-to-ligand charge-transfer (MLCT) state character to the lowest excited state.Although techniques of the WOLEDs have been extensively investigated, a comprehensive theory on the mechanism of photophyscis and tunable emission is still in its infancy.[13] Herein, we report a quantitative theoretical model, based on Fçrster theory of nonadiabatic transition/energy transfer and accurate electronic structure calculations, to explore how the single-dopant Pt-4 WOLED functions efficiently and meanwhile how the nonadiabatic transition/ energy transfer tune its phosphorescent color. Table 1 summarizes the vertical and adiabatic transition energies for the Pt-4 monomer as well as other properties. To assess the accuracy of the electronic structure calculations, we first analyze the optical absorption characteristics.Two charge transfer (CT) states, S MLCTy , and S MLCTx , resulting from the excitation of the d yz and d xz electrons, are characterized by the respective electron migration towards the ligand along the y and x directions within the molecular plane (see Figure 1 for the Cartesian axes). The ...

show abstract

Section: à07mentioning

confidence: 98%

“…[18] The present model of nonadiabatic transition and energy transfer quantitatively accounts for the three components of the photoluminescence spectra of Pt-4 [17] including monomer-like radiative transition below 500 nm (distance > ca. 4.5 nm, low concentration), dimer emission band at wavelength longer than 600 nm (distance < ca.…”

Section: à07mentioning

confidence: 99%

Energy Transfer Tunes Phosphorescent Color of Single‐Dopant White OLEDs

Han

Chen

Shen

et al. 2011

Chemistry A European J

View full text Add to dashboard Cite

show abstract

“…19 Moreover, ϕ PL (excimer) = 74% > ϕ PL (monomer) = 49% has recently been reported for another Pt complex (Pt L 26 Cl). 20 Broad featureless emission from B-M excited states (excimers and dimers) becomes therefore even more attractive to the manufacturing of effi cient red OLEDs and NIROLEDs 18,19 as well as to the improvement of WOLEDs where a combination of molecular PH with the red-shifted excimer PH yields emission approaching white light based on single emissive dopant (see Fig. 10.3 ).…”

Section: Introductionmentioning

confidence: 99%

Tuning the colour and efficiency of OLEDs * *This chapter is dedicated to the memory of Professor Jan Kalinowski, who died on 18 December2010.

Cocchi¹

2013

Organic Light-Emitting Diodes (OLEDs)

Self Cite

View full text Add to dashboard Cite

“…3 Such a possibility depends strongly on the chemical structure of the chromophore as well as the surrounding environment, thus differing signicantly from one material system to another. [9][10][11] The nature of solid-state interactions in these systems is oen ascribed to the Pt/Pt metal interaction or p-p interactions of ligands or both. For instance, Swager et al have reported strong emission from excimers in conjugated polymer (CP) structures with ring systems that prevent ground state interactions.…”

Section: Introductionmentioning

confidence: 99%

Deep-red excimer emission from Ir doped organic light-emitting devices

2013

View full text Add to dashboard Cite

Here we report on the concentration-dependent photoluminescence and electroluminescence emission from blends of a conjugated polymer and an Ir(III) organic complex. Energy transfer from the polymer host to the phosphor molecule leads to emission of the latter falling into two pools: the characteristic single molecule emission and a low-energy vibronically unstructured emission band. We provide complementary photophysical and device characterization of the low-energy emissive state. The unchanged absorption spectrum upon phosphor concentration changes, the emission enhancement of the low-energy band upon doping (observed both under electrical or photo-excitation), together with a decrease of its relative electroluminescence emission as the temperature is lowered, and, the strikingly different photoluminescent dynamics associated with both emission bands suggest the formation of excimers at high doping ratios. Owing to the non-planar coordination structure of Ir(III) complexes we conjecture that these excimer emissions must arise from p-p stacking of nearly parallel rings of the cyclometallated ligands. We highlight the significance of this low-energy emission in the development of deep-red electroluminescent devices as inferred from Commission International de l'Eclairage coordinates equal to (0.66; 0.34). † Electronic supplementary information (ESI) available: Inuence of the concentration by weight of PF26 : IrDBQ solutions on electroluminescence, UV-VIS absorption spectra of blended lms, the 1 H Nuclear Magnetic Resonance (NMR) spectrum of IrDBQ, and luminance-voltage/density current-voltage characteristics of doped diodes. See

show abstract

Bi-molecular emissive excited states in platinum (II) complexes for high-performance organic light-emitting diodes

Cited by 57 publications

References 31 publications

Energy Transfer Tunes Phosphorescent Color of Single‐Dopant White OLEDs

Energy Transfer Tunes Phosphorescent Color of Single‐Dopant White OLEDs

Tuning the colour and efficiency of OLEDs * *This chapter is dedicated to the memory of Professor Jan Kalinowski, who died on 18 December2010.

Deep-red excimer emission from Ir doped organic light-emitting devices

Contact Info

Product

Resources

About