Progress in semiconductor technology introduces a new platform for quantum optics studies in solid state: a quantum dot strongly coupled to a cavity mode. We present a numerically solvable model for the combined electron, photon, and phonon dynamics. For a cavity mode prepared in a Fock state, the model reproduces the Jaynes-Cumming solution and interaction with a phonon bath leads to a higher value for the intensity-intensity correlation function: g;(2)(0). In contrast, for an initial thermal photon distribution, the phonon-bath interaction gives a counterintuitive reduction in g;(2)(0), resulting in the classical photon distribution evolving into a nonclassical one.