Various functional precursors based on polythiophene derivatives are designed to prepare carbon dots (C-dots) with tunable emissions ranging from blue to near-infrared (NIR) under a single excitation wavelength (400 nm). The as-prepared C-dots demonstrate homogeneous size, superior optical properties, excellent water solubility, and low cytotoxicity. Thus, the C-dots are candidate for bio-imaging. A tunable photoluminescent mechanism is proposed to result from variations in surface states and N contents. 

Nanoscale, 2015