Colloidal nanocrystals are versatile building blocks to design infrared optoelectronic devices. When their dimension is reduced below the Bohr radius, quantum confinement occurs, thus providing size-tunable optoelectronic properties. In particular, mercury telluride nanocrystals offer a broadly tunable absorption, going from 1.5 eV to 20 meV. Recent progress in material growth and in surface chemistry has allowed to enhance IR detectors performances. Still, advancement in several aspects is needed to further improve performance, maximize signal-to-noise ratio and speed up the photoresponse time. The need for such improvements has led to a variety of designs for IR detectors, ranging from photoconductive to photovoltaic devices.