Quantum emitters (QEs) in condensed matter systems naturally interact strongly with phonon modes of their host material. This degrades quantum effects that are crucial for quantum technology applications, including photon indistinguishability and the coherence between electronic states. It is therefore important to accurately describe the impact of electron-phonon interactions on both dynamical and optical properties of a QE if we are to assess their viability as scalable quantum technologies. In this talk I will outline how methods from open quantum systems theory can be applied to model the impact of phonon processes in QEs. In particular, I will discuss how electron-phonon interactions are modified in the presence of photonic structures and strong light-matter coupling.