Lead Sulphide Quantum Dots As an important IV_VI semiconductor, lead (PbS) has attracted much attention for many years due to its strong absorption cross-section, strong quantum confinement of both electrons and holes and a tunable band gap from the near infrared (NIR) to the visible spectral region.

Lead Sulphide Quantum Dots shown some novel and excellent optical and electronic properties, such as IR photodetectors, photovoltaics, electroluminescence, photoluminescence, thermal and biological images and display devices. The photoluminescence (PL) spectra of PbS QDs with different particle sizes, being quantum confinement effect, nearly cover a broad band from 800 to 1600 nm, which matches well with the whole optical communication window.

Lead Sulphide Quantum Dots In particular, Qdots that emit in the second near-infrared biological window (NIR-II, 1000-1400 nm, photon energy: 1.24-0.89 eV) are extremely attractive for in vivo fluorescence imaging.

Lead Sulphide Quantum Dots Due to the greatly reduced light absorption and scattering together with nearly zero biological auto-fluorescence background, leading to the deepest light penetration into body with significantly increased imaging contrast, fidelity and resolution. 6-9 Compared to the widely used NIR-I emitters (ca. 650-900 nm), the NIR-II reporters can provide much higher imaging signal-to-noise (S/N) ratio and spatial resolution in vivo.

Lead Sulphide Quantum Dots Combining attractive properties of high brightness, robust photostability and excellent biocompatibility, this new NIR-II emitting Qdot is highly promising in accurate disease screening and diagnostic applications.