The dual of Brown representability for homotopy categories of complexes

We call product generator of an additive category a fixed object satisfying the property that every other object is a direct factor of a product of copies of it. In this paper we start with an additive category with products and images, e.g. a module category, and we are concerned with the homotopy category of complexes with entries in that additive category. We prove that the Brown representability theorem is valid for the dual of the homotopy category if and only if the initial additive category has a product generator.