One of the main challenges in applying fluorescence microscopy to large biological specimens including tissues and whole organisms, which is the latest focus in fluorescence imaging field, is the absorption and scattering of both excitation light and fluorescence emission by the specimens. Oneofthe best ways to capture high quality images through thick biological specimens is to use shortwave infrared (SWIR, 1,000-1,700 nm) fluorescence since both absorption and scattering of light are highly suppressed in this wavelength region. However, fluorophores that are available for SWIR fluorescence imaging at the moment are very limited. In this project, we develop new SWIR emitting fluorophores using conjugated polymer materials. Through in depth photophysical characterization including single-molecule SWIR fluorescence microscopy, we aim to develop new SWIR-emitting conjugated polymer nanoparticles. Based on the photophysical characteristics of the developed materials, we also aimtodevelop new SWIR fluorescence imaging techniques including time-gated imaging.