Critical review of the determination of photoluminescence quantum yields of luminescent reporters

Abstract

A crucial variable for methodical performance evaluation and comparison of luminescent reporters is the photoluminescence quantum yield (Φ pl). This quantity, defined as the number of emitted photons per number of absorbed photons, is the direct measure of the efficiency of the conversion of absorbed photons into emitted light for small organic dyes, fluorescent proteins, metal-ligand complexes, metal clusters, polymeric nanoparticles, and semiconductor and up-conversion nanocrystals. Φ pl determines the sensitivity for the detection of a specific analyte from the chromophore perspective, together with its molar-absorption coefficient at the excitation wavelength. In this review we discuss different optical and photothermal methods for measuring Φ pl of transparent and scattering systems for the most common classes of luminescent reporters, and critically evaluate their potential and limitations. In addition, reporter-specific effects and sources of uncertainty are addressed. The ultimate objective is to provide users of fluorescence techniques with validated tools for the determination of Φ pl, including a series of Φ pl standards for the ultraviolet, visible, and near-infrared regions, and to enable better judgment of the reliability of literature data.

Three‐in‐One Crystal: The Coordination Diversity of Zinc Polypyridine Complexes

“…All measurements were performed under magic‐angle conditions (polarization at 0° for the excitation and 54.7° for the emission channel). The luminescence quantum yield was determined with an Ulbricht integrating sphere (Quantaurus‐QY C11347‐11, Hamamatsu), and the relative uncertainty was estimated to be 5 %. The ESI MS spectra were recorded with a Micromass Q‐TOF‐Ultima spectrometer.…”

The origin of emissive states of carbon nanoparticles derived from ensemble-averaged and single-molecular studies

“…Characterizing the quantum yield of CDs emission in solutions, many authors use the reference method by comparing the integrated emission intensities of the studied sample and of the standard with the known quantum yield 55 . Φ is defined as the ratio of the number of emitted quanta to the whole number of the quanta absorbed and, in other words, as the probability to emit one photon in the form of fluorescence after one photon absorption.…”

Excitation wavelength dependence of the photoluminescence quantum yield and decay behavior of CdSe/CdS quantum dot/quantum rods with different aspect ratios

“…[22][23][24] Low ΦPL of QDs and QDQRs indicate insufficient surface passivation and the formation of energy states within the band gap that can act as trapping sites for photogenerated charge carriers. Within the last decades, the question if QDs and QDQRs show an excitation wavelength (λexc) dependence of ΦPL, 21 has been addressed by several groups with controversial results. [25][26][27][28] For example, a strong λexc dependence of ΦPL was observed by Hoheisel et al for a series of CdSe QDs with radii from 0.9 nm up to 2.6 nm including a considerably diminished PL efficiency for excitation within the absorption continuum, i.e., to higher excited states relative to the band edge.…”

“…21,33 Also other SCNC-specific factors related to the number and energetic position of surface states and their surface chemistry, morphology, and constitution, 31 can affect ΦPL. For example, in the case of QDQRs, the competition between exciton diffusion through the elongated shell to the core and exciton trapping within the shell can lead to an exciton localization efficiency that depends on the length of the QDQR and can affect ΦPL.…”