Efficient multiphoton absorption of near-infrared emitting Cu-doped ZnInS/ZnS nanocrystals

Abstract

Due to their unique optoelectronic properties, doped semiconductor nanocrystals (NCs) are promising fluorescent probes for deep-tissue bioimaging applications. However, studies on the photophysical properties of cadmium-free doped NCs are scarce. In this study, we synthesized and studied the photophysical properties of one type of cadmium-free doped NCs (Cu: ZnInS/ZnS NCs), which exhibit near infrared-I (NIR-I) emission at 730 nm and long emission lifetime up to 1.38 μs. Femtosecond transient absorption spectra revealed a strong exciton coupling effect between the Cu2+ ions and the ZnInS/ZnS host, with a fast energy transfer time of ≈100 ps. More importantly, Cu: ZnInS/ZnS NCs exhibit efficient volume-normalized two- and three-photon absorption cross-sections in NIR-I (800–900 nm) and NIR-III regions (1600–1990 nm), with maximum values up to 6.9 GM nm−3 at 800 nm and 1.1 × 10−80 cm6 s2 photon−2 nm−3 at 1600 nm, respectively. This study can shed light on the exploration of novel environmentally friendly doped NCs for deep-tissue bioimaging applications.

In Vivo Three‐Photon Imaging of Lipids using Ultrabright Fluorogens with Aggregation‐Induced Emission

“…Under NIR‐II femtosecond laser (1200 nm) excitation, TPAPhCN dots in aqueous medium emitted ultrabright three‐photon fluorescence with a large three‐photon absorption cross section of 2.45 × 10 −73 cm 6 s 2 photon −2 based on single dot, which is comparable to several reported quantum dots. [ 23a,29 ] TPAPhCN dots also had excellent photostability under NIR‐II laser irradiation compared to commercial Qtracker 625 and Alexa Fluor 647. In addition, TPAPhCN dots showed long‐term stability in aqueous medium, which is revealed by their negligible changes in absorption and emission spectra after 6 month storage (Figure S41, Supporting Information).…”

Transition Metal Doping in CdS Quantum Dots: Diffusion, Magnetism, and Ultrafast Charge Carrier Dynamics

“…Fundamental thermodynamic questions like how the bond lengths should vary for different dopants within the same host or how the diffusivity of the dopants should change are yet to be understood. Similarly, although several reports have investigated the carrier dynamics in the individual TM-doped II–VI semiconductor QDs, − a comprehensive study that tries to harmonize the same of different TM dopants is still lacking.…”

InP Semiconductor Nanocrystals: Synthesis, Optical Properties, and Applications

“…Alternatively, environmentfriendly semiconductor NCs, such as InP, CuInS 2 , and ZnInS/ZnS NCs, have shown excellent development opportunities due to their low toxicity. [10][11][12] Among them, InP NCs are considered as the most promising candidates to replace Cd/Pb-based NCs due to their advanced optical properties. [13] Compared with Cd/Pb-based NCs, InP NCs have received less attention due to their complicate synthesis.…”