Accurate, Precise, and Verifiable Photoluminescence Efficiency of Colloidal Quantum Dots Sols by Photothermal Threshold Quantum Yield Analysis

Abstract

Colloidal quantum dots (QDs) have become multipurpose luminophores that combine a broad excitation with a narrow emission spectrum. Applications in displays, lighting, or solar-energy conversion, however, require quantum dots that have a photoluminescent quantum yield (PLQY) approaching unity. This need makes the accurate, precise, and verifiable determination of the photoluminescence efficiency of QDs of utmost importance for the field. Here, we describe photothermal threshold quantum yield as a calorimetric method for measuring the PLQY of QDs in liquid dispersions. Taking the example of InP-based core/shell QDs, we detail the principles behind the analysis, and we benchmark results relative to the spectroscopic determination using an absolute PLQY measurement with an integrating sphere. We argue that the accuracy of the method for highly efficient emitters, and the simplicity of the data and the data analysis make photothermal threshold quantum yield well suited for certifying the photoluminescence efficiency of QDs.