Bright, Stable, and Active: Surface Engineered Blue-Emitting InP Quantum Dots for Photoinduced Charge Separation in Water

Abstract

Unique optoelectronic and surface properties of quantum dots (QDs) make them promising materials for several scientific explorations, especially in solar energy research. Understanding the dynamics of charge carrier separation and extraction is essential to enhancing the performance of QD-based light-harvesting devices. Herein, we investigate the photoinduced electron transfer (PET) process in blue-emitting QDs based on indium phosphide (InP)─the latest addition to luminescent materials. The light-harvesting system comprises electrostatically bonded blue-emitting InP/ZnS core/shell QDs as electron donors and methylene blue (MB) dye as electron acceptors. The PET process is occurring in a hundreds of picoseconds time scale with ∼60% efficiency. Broadband femtosecond transient absorption spectroscopy confirms the PET from QD to MB, as evidenced by the emergence of a microsecond long-lived excited state absorption feature at ∼450 nm, characteristic of the reduced MB+• semiquinone. Our studies provide valuable insights into the charge-transfer dynamics of blue-emitting InP/ZnS QDs, encouraging their use in photovoltaic and photocatalytic applications