Quantaurus-QY was developed as a compact, easy-to-use system with a small footprint based on Hamamatsu's established C9920-02/03 systems for measuring absolute photoluminescence quantum yields. Operating this system is simple: load a sample and press the start button to measure the photoluminescence quantum yields, excitation wavelength dependence, photoluminescence excitation spectrum and other properties in a short period of time.
The Quantaurus-QY multichannel detector captures the sensitivity-compensated spectrum and calculates the quantum yield in a process that instantaneously finds the absolute value of the quantum yield. Dialog-style dedicated software keeps the measurement process simple. The software-controlled monochromator allows the sample to be excited by various excitation wavelengths. The wavelength dependence of the quantum yield and excitation spectrum can then be automatically measured. The device handles solution, thin-film and powder samples. With a Dewar flask holder, solution samples can be cooled by liquid nitrogen to −196 °C (77 K). Two product types are available according to the wavelength range for sample excitation and photoluminescence: the standard type, C11347-11, covers the wavelength range 300–950 nm, whereas the near-infrared type, C11347-12, covers the wavelength range 400–1,100 nm.
Measuring the absolute photoluminescence quantum yields of light-emitting materials
In the development of new light-emitting materials, it is often essential to improve their photoluminescent efficiency. This requires accurate techniques for measuring the quantum yield (the ratio of the number of photons emitted through photoluminescence to the number of photons absorbed by the light-emitting material). Quantaurus-QY includes an excitation light source consisting of a xenon lamp and a monochromator, an integration sphere with optional nitrogen gas flow and a multichannel detector capable of simultaneous multiwavelength measurement, all integrated into a single package. The system utilizes dedicated software for making the measurements. The detector is a cooled, back-thinned CCD sensor and so makes instantaneous measurements with high sensitivity and a high signal-to-noise ratio.
The Quantaurus-QY measures the absolute photoluminescence quantum yield of light-emitting materials, while utilizing an integrating sphere to measure all luminous flux. The Quantaurus-QY automatically controls the excitation wavelengths, and incorporates a wide selection of analysis functions, including photoluminescence quantum yield measurement, excitation wavelength dependence, photoluminescence spectrum and photoluminescence excitation spectrum.
Quantum yield measurements
Quantum yield measurements are made in a wide range of fields to meet needs in development and research applications. Typical applications include improving quality in various types of light-emitting materials such as organic electroluminescent materials, white LEDs and phosphors for flat-panel displays; researching organic metal complexes; evaluating fundamental characteristics of dye-sensitized solar cells; and measuring fluorescent probe efficiency in biological fields. Our long and proven record in quantum yield measurements is the reason our products are favoured by many users in a wide range of fields. Below is a list of measurement examples.
Phosphorescence quantum yield of phosphorescent materials for organic LEDs1. Iridium complex is the focal point of much recent research as a promising phosphorescent material for organic LEDs. We measured its phosphorescence quantum yield (ΠP) in dichloroethane solution. Results showed the blue material Ir(Fppy)3 and green material Ir(ppy)3 indicate high ΠP values of approximately 0.97 and 0.89, respectively. The red material Btp2Ir(acac), on the other hand, yielded a low ΠP value of approximately 0.32. As these phosphorescent materials form a triplet state with an efficiency of almost 100%, the decrease in ΠP in Btp2Ir(acac) is clearly due to efficient intersystem crossing from T1 to S0 (that is, a non-radiating transition from a triplet state T1 to a ground state S0).
Observing high-efficiency intermolecular energy transfer in a rare-earth complex. Rare-earth complexes are attracting much recent attention as a clean energy conversion material utilizing ligands for efficient photo-excited energy conversion that emits light with a sharp peak in the visible region. We measured the emission quantum yield of the rare-earth complex Eu(Phen)2(NO3)3 in a powder state. Direct excitation on the 1,10-phenanthroline (Phen) resulted in a europium (Eu) emission quantum yield of approximately 0.8. No luminescence from Phen was observed, so we conclude that energy transfer from Phen to Eu occurred at a high efficiency of over 80%.
Quantum yield measurement of fluorescent bioprobe. Fluorescent probe for enzyme reaction detection, in which quantum yield provides a comparative measurement. Fluorescent probe TG–βGal for β-galactosidase activity detection is non-luminescent (Πf = 0.01) but exhibits strong fluorescence after reacting with β-galactosidase. The quantitative difference in amounts of light emitted before and after the enzyme reaction can be found by compounds comparing their quantum yields Πf.
Re-evaluation of luminescence quantum yield of representative standard solutions2. The C9920-0X (X = 2,3) consists of an excitation light source, an integrating sphere and a multichannel spectrometer, and measures the absolute photoluminescence quantum yield. By using the C9920-0X, the quantum yields of fluorescence standard compounds in solution were measured. The compounds are commonly used as fluorescence standards in quantum yield measurements based on a relative method. For most of the compounds, the quantum yield measured by the C9920-0X shows excellent agreement with the values given in the literature, proving the high reliability of the C9920-0X.
Fluorescence quantum yield and levigation effect on p-terphenyl and anthracene single crystals3. We utilized high-purity single crystals of the typical organic materials p-terphenyl and anthracene to determine their respective fluorescence quantum yields. Measuring the p-terphenyl resulted in a fluorescence quantum yield of 0.67 for this high-purity single crystal. Levigating this single crystal to a fine powder increased the fluorescence quantum yield to 0.80. On the other hand, levigating the high-purity, single crystal anthracene decreased the fluorescence quantum yield from 0.64 to 0.27. Measuring the p-terphenyl showed a higher fluorescence quantum yield and appearance of structures on the short wavelength side of the fluorescence spectrum. So this higher fluorescence quantum yield was possibly caused by the fine powder from levigation that acts to inhibit re-absorption. Examining the anthracene revealed another luminescent component at longer wavelengths caused by levigation in addition to the usual luminescent components on shorter wavelengths of the fluorescence spectrum. This luminescent component on the lower wavelengths resembles the fluorescence spectrum of anthracene dimer and so was found to be luminescence from a dimer state. This fact proves that the decrease in fluorescence quantum yield of anthracene single crystal was caused by dimers induced by levigation that formed structural flaws and acted as a centre for light extinction.
Phosphorescence quantum yield measurement of benzophenone at −196 °C (77 K). Phosphorescence quantum yields in benzophenone organic solution were measured at room temperature (22 °C; 295 K) and at a low temperature (−196 °C; 77 K) and both compared on the graph. Benzophenone is known to generate a triplet excitation state at a high efficiency (ΠISC to 1.0) after being excited by light from the ground state to the singlet state. Observing phosphorescence from general organic compounds is usually difficult because phosphorescence is a forbidden transition. In benzophenone, a phosphorescence spectrum, though weak, was definitely observed (ΠP to 0.01). The result also shows that phosphorescent intensity greatly increased at low temperature compared to room temperature and produced a high phosphorescence quantum yield (ΠP > 0.8).
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Katoh, R., Suzuki, K., Furube, A., Kotani, M. & Tokumaru, K. J. Phys. Chem. C 113, 2961–2965 (2009).
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Suzuki, K. Quantaurus-QY: Absolute photoluminescence quantum yield spectrometer. Nature Photon 5, 247 (2011). https://doi.org/10.1038/nphoton.an.2011.1