Colloidal Quantum Dots Thin Films: A Theoretical Insight Into Optical Efficiency for Optoelectronic Applications

A growing number of scientific publications have shown during this last decade the potential of colloidal quantum dots (QDs) thin films for optical sensing, such as photonic applications, multispectral imaging, or infrared (IR) depth imaging. In this context, it appears interesting to consolidate these experimental results by describing theoretically how the performance of QD photodetectors is affected by the features of QD thin films, such as the QD diameter, QD size polydispersity, inter-QD distance, and QD materials. This article presents an analytical model of QD optical indices combining tight-binding simulations and effective medium theory, enabling an evaluation of the optical efficiency of single QDs, QD thin films, QD photodetectors, and a comparison of QD thin films with conventional bulk semiconductors. It provides useful parameterization of a large variety of QD materials allowing the extraction of QD film properties from ellipsometry measurements or photodiode quantum efficiency values. Furthermore, it contributes to the understanding of the origins of the performance-governing parameters of QD photodetectors and helps anticipate engineering development to improve it.