A Dual Fluorescence Temperature Sensor Based on Perylene/Exciplex Interconversion

Chandrasekharan, Nirmala; Kelly, Lisa A.

doi:10.1021/ja016153j

Cited by 191 publications

(109 citation statements)

References 7 publications

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“…The fluorescence lifetimes of DPA, rubrene, and TIPS-pentacene are 1.8, 17.5, and 1.4 ns, respectively. We note that the PL of perylene originates from an exciplex state, [23] with biexponential decay lifetimes of 1.5 and 10.7 ns. To examine whether triplet excitons in these emitters contribute to the EL process, we performed transient-EL measurements for FuLEDs based on PVK:emitter blends.…”

Section: Doi: 101002/adma201605987mentioning

confidence: 87%

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

et al. 2017

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probability of a triplet pair forming a singlet) in solution is >60%, much higher than the spin-statistical prediction of 25% (one pair of triplets collides to form one of the four states: one singlet S 1 and three triplets T 1 , assuming higher triplet and quintet states are inaccessible). Practical application of solar energy conversion requires the TTA-UC material to be in solid state rather than in solution phase. However, the TTA-UC quantum yield of solidstate systems remains low, typically below 5%, [10] and is moderately high (about 10%) in only one example. [19] To achieve high efficiencies, high excitation intensities (200 mW cm −2 or above) are commonly required. These imply that in solid state, the experimentally observed reaction efficiency of TTA-UC was up to about 20%, below the 25% spin-statistical limit.To achieve highly efficient triplet fusion (TTA-UC) in OLEDs and other TTA upconverters, we consider four criteria for the selection of emitters: (1) high fluorescence quantum yield, (2) short singlet lifetime, (3) long triplet lifetime, and (4) the energy of two triplet excitons, 2E(T 1 ) lies slightly above that of the singlet exciton, E(S 1 ), but below the second triplet state, E(T 2 ) (and also the energies of any spin-quintet states) (E(S 1 ) ≲ 2E(T 1 ) < E(T 2 )). The first and second criteria are prerequisites for efficient fluorescence. The third criterion is essential for the accumulation of a sufficiently high triplet population density required for rapid triplet-triplet collision processes. The fourth criterion ensures that higher-lying triplet or quintet states do not provide loss channels. The spin states of the triplet excitons give in principle nine spin configurations for the interacting triplet exciton pair, five associated with a quintet, three with a triplet, and one with the singlet state. It is generally considered that the quintet is always higher in energy than the initial triplet pair, so is neglected. If there are no energetically accessible higher-lying triplet states at E(T 2 ), we expect only the S 1 and T 1 excitons to form. Triplets produced from this reaction can be recycled and participate in a further fusion reaction. [7] The basic working principle of a triplet fusion LED (FuLED) is illustrated in Figure 1a. The initial stage (Stage I) of the device operation includes charge injection and exciton formation. Exciton formation on the emissive molecules may occur directly or indirectly through an additional exciton transfer step from a host material. If a host material is present, the S 1 and T 1 of the host are required to be higher than that of the emitter to allow efficient host-emitter energy transfer and to ensure long triplet lifetime of the emitter (Criterion 3 discussed above). The 25% singlet population can be converted to light emission (and nonradiative losses) from the singlet channel immediately, resulting in prompt electroluminescence (EL). The 75% triplet excitons remain nonemissive, but the population of triplets is When an organic light-emitting dio...

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Section: Doi: 101002/adma201605987mentioning

confidence: 87%

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

et al. 2017

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“…74 The ratiometric variation of the emission intensities of monomer-exciplex species was studied using a two-state equilibrium model in the temperature range 290-360 K with Table 2 and Fig. 1).…”

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Thermometry at the nanoscale

et al. 2012

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Non-invasive precise thermometers working at the nanoscale with high spatial resolution, where the conventional methods are ineffective, have emerged over the last couple of years as a very active field of research. This has been strongly stimulated by the numerous challenging requests arising from nanotechnology and biomedicine. This critical review offers a general overview of recent examples of luminescent and non-luminescent thermometers working at nanometric scale. Luminescent thermometers encompass organic dyes, QDs and Ln 3+ ions as thermal probes, as well as more complex thermometric systems formed by polymer and organic-inorganic hybrid matrices encapsulating these emitting centres. Non-luminescent thermometers comprise of scanning thermal microscopy, nanolithography thermometry, carbon nanotube thermometry and biomaterials thermometry. Emphasis has been put on ratiometric examples reporting spatial resolution lower than 1 micron, as, for instance, intracellular thermometers based on organic dyes, thermoresponsive polymers, mesoporous silica NPs, QDs, and Ln 3+ -based up-converting NPs and b-diketonate complexes. Finally, we discuss the challenges and opportunities in the development for highly sensitive ratiometric thermometers operating at the physiological temperature range with submicron spatial resolution.

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“…12,13 NSOM measurements using commercially available gold-coated chemically etched fiber optic probes revealed no significant blueshift in the emission spectra, suggesting sample heating near the aperture is less than 40 K. Here we extend these measurements using a thermochromic polymer incorporating perylene and N-allyl-N-methylaniline ͑NA͒ that exhibits "two-color" emission. 14 As such, ratiometric measurements of the peak intensities enable precise characterization of probe heating directly at the NSOM aperture.…”

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confidence: 99%

Sample heating in near-field scanning optical microscopy

Erickson

Dunn

2005

Applied Physics Letters

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Heating near the aperture of aluminum coated, fiber optic near-field scanning optical microscopy probes was studied as a function of input and output powers. Using the shear-force feedback method, near-field probes were positioned nanometers above a thermochromic polymer and spectra were recorded as the input power was varied. Excitation at 405 nm of a thin polymer film incorporating perylene and N-allyl-N-methylaniline leads to dual emission peaks in the spectra. The relative peak intensity is temperature sensitive leading to a ratiometric measurement, which avoids complications based solely on intensity. Using this method, we find that the proximal end of typical near-field probes modestly increase in temperature to 40-45°C at output powers of a few nanowatts ͑input power of ϳ0.15 mW͒. This increases to 55-65°C at higher output powers of 50 nW or greater ͑input power of ϳ2-4 mW͒. Thermal heating of the probe at higher powers leads to probe elongation, which limits the heating experienced by the sample.

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A Dual Fluorescence Temperature Sensor Based on Perylene/Exciplex Interconversion

Cited by 191 publications

References 7 publications

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

Efficient Triplet Exciton Fusion in Molecularly Doped Polymer Light‐Emitting Diodes

Thermometry at the nanoscale

Sample heating in near-field scanning optical microscopy

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