Cooled CCD’s have been around for a long time and it would appear that the main use is in reducing dark current. This makes a cooled CCD excellent for bio and chemo luminescense, DNA sequence imaging, x-ray imaging, radiology and in particular astronomy.
The following information has been copied from an ad for a monochrome Peltier cooled CCD camera:
This monochrome CCD camera utilizes Peltier cooling to dramatically reduce dark current noise that accumulates during extended integration periods. The result is a high performance video imaging camera with low noise, wide dynamic range, low-light capability, and spectral response to near IR.
Design and construction of the cooled camera
module lowers the sensor temperature to reduce dark current noise that accumulates during extended integration periods. The sensor operates at 5° C in a 25° C ambient environment, resulting in a reduction of dark current to about one-eighth that without cooling. Using a Peltier cooler, along with a natural convection, dual-section heat sink, the sensor is able to collect more light to display as a reduced noise video image.