TITLE: Synthesis and Characterization of Indium Phosphide-Based Quantum Dot Heterostructures
ABSTRACT: Colloidal semiconductor nanocrystal quantum dots (QDs) have been extensively studied for applications in biosensing and imaging. Indium phosphide (InP) QDs have a large Bohr radius of ~10 nm and a bulk band gap of 1.35 eV, which makes their emission size-tunable in a wide spectral range, providing superior color tuning compared to that of CdSe QDs. However, differences in brightness, defined as the product of molar extinction coefficients and quantum yield (QY) across emitters of different colors, remain a roadblock to their widespread use in multiplexed imaging applications. The large absorption cross-section of red emitters often makes them significantly brighter than their smaller, green/yellow emitting counterparts, limiting the possibility of simultaneous detection of different colors. This study addresses this problem by drawing a quantitative comparison of absorption properties of different type-I QDs, aiming to make these heterostructures suitable for accurate imaging and sensing applications. Tuning of the absorption cross-section and extinction coefficient, along with brightness tuning of the QDs has been performed through synthesizing a series of QDs with a combination of core sizes, shell thicknesses, and compositions. The successful completion of this project will result in a rainbow of brightness-matched cadmium-free QDs/QSs emitting from green through the NIR-I window, generating novel fluorophores for multiplexed imaging applications.
Allison M. Dennis, MSE/BME; Malika Jeffries-EL, MSE/Chemistry; Tyrone Porter, MSE/ME; Sahar Sharifzadeh, ECE/MSE