Absolute Electrochemiluminescence Quantum Efficiency of Au Nanoclusters by Means of a Spectroscopy Charge-Coupled Device Camera

Abstract

Currently, the electrochemiluminescence (ECL) efficiency of a luminophore is evaluated by measuring the ratio of ECL intensity generated by a certain number of electrons injected. Then, this ratio is compared to that of the commercial luminophore, Ru(bpy)3 2+ under the same test conditions. However, the ECL intensity from a luminophore will be different on every instrumental setup due to wavelength-specific interaction of light with photodetectors. Also, previous absolute ECL techniques require multiple instruments, each of which has its own wavelength-specific light losses leading to complicated hardware and calculation requirements. Herein, this paper presents an absolute way to evaluate the ECL quantum efficiency (QE), permitting researchers to quickly compare ECL results and elucidate ECL mechanisms. The accuracy and precision of this new physical strategy is verified with the well-studied Ru(bpy)3 2+ to find an ECL QE of 0.64%. The strategy was then exemplified with Au25 0(SC2H4Ph)18 to represent a difficult spectroscopic challenge and this ECL QE was found to be 0.0062%. Finally, Ru(bpy)3 2+ ECL QE at different TPrA concentrations was evaluated to understand how the TPrA concentration affects the ECL QE of Ru(bpy)3 2+. Significant Ru(bpy)3 2+ ECL QE decreases were viewed from 3.2 × 10–3% at 6.25 mM TPrA to 6.5 × 10–6% at 200 mM TPrA likely due to high excited state quenching. Along with our previous publications on Au cluster ECL, discussed are factors influencing the ECL intensity such as the diffusion of electroactive molecules, the stability of radicals, the reactivity of excited states, and the analyte’s reactivity. Profound variations were observed on this finding, which has large implications for past, current, and future relative ECL efficiencies also discussed in length.

Elucidation of an Aggregate Excited State in the Electrochemiluminescence and Chemiluminescence of a Thermally Activated Delayed Fluorescence (TADF) Emitter

“…The absolute ECL quantum efficiency (Φ ECL ) of TPA-ace-TRZ was then determined to be 0.028% (Table ), using our standardized spectrograph/CCD camera setup . The Φ ECL of TPA-ace-TRZ is approximately 9-fold stronger compared to the reference system of [Ru­(bpy) 3 ] 2+ /BPO.…”

Electrochemiluminescence Distance and Reactivity of Coreactants Determine the Sensitivity of Bead‐Based Immunoassays

“…The relative ECL efficiencies of five tertiary amines were also evaluated using the method reported in prior works. [59][60][61] Taking the ECL efficiency of Ru(bpy) 3 2 + /TPrA as the standard (defined as 100 %), the relative efficiencies were determined to be 149 %, 142 %, 31 % and 50 % for DBAE, BIDE, TEOA and BIS-TRIS, respectively (see Section S12 and Figure S27). DBAE is the most efficient coreactant among five, but it should be mentioned that specific experimental conditions, such as concentration and electrochemical method used, dramatically affect the measured efficiency.…”

Nitrogen- and sulfur-doped graphene quantum dots for chemiluminescence

“…The total photons were obtained by integration of the light quanta-wavelength curves with the assistance of custom programs in MATLAB software (version 2021b, MathWorks Inc., Natick, MA, USA) developed in our group, similar to those for determining absolute electrochemiluminescence efficiencies. 8,35,36…”