Determination of absolute quantum yields of luminescing nanomaterials over a broad spectral range: from the integrating sphere theory to the correct methodology

摘要

Determination of fluorescence or photo- and electro-luminescence quantum yield (QY) is ofincreasing importance for standardization of novel light-emitting materials like semiconductorquantum dots. The most straightforward spectroscopic QY measurement technique is based onthe exploitation of an integrating sphere (IS). We propose a compact set-up and procedure forreliable measurements of QY over a broad excitation spectral range which uses excitation bylight-emitting diodes. Starting from the general IS theory we show that (i) a variable excitationpattern has no fatal influence on the QY determination and (ii) a simple two-configurationexperiment is an adequate basis of the correct experimental procedure. Then we give guidelinesfor the QY experiment and calculations as well as a few practical examples and error analysis.Our comprehensive description of absolute luminescence QY techniques based on the IS theoryhas a general applicability not restricted to the apparatus described in this paper.