We present the performance characteristics of two examples from a special class of photon detector, based on the blocked impurity band (BIB) concept. Recent results are presented on Si:Sb BIB detectors covering the 2 to 50 micrometers wavelength range, and on Ge:Ga BIB detectors that are sensitive in the 50 to 220 micrometers range. The inherent properties of these BIB detectors make them a natural choice for infrared astronomy; minimal sensitivity to ionizing radiation, compatibility with large format (128 X 128) arrays, low dark currents and high detective quantum efficiencies, combined with a lack of anomalous behavior. The detector characteristics are discussed in terms of a standard BIB performance model. Both detector types appear to have unique potential for astronomy applications.