Two-dimensional (2D) perovskites assembled with hydrophobic bulky organic cations demonstrate much enhanced ambient stability and anisotropic carrier transport, making their devices highly promising. However, photovoltaic (PV) devices scaling up to modules using 2D perovskites lag far behind their 3D counterparts. Hence, improving the scalability and efficiency of 2D perovskite PV devices is a challenging topic. In this Perspective, from the insights of multiscale structures of 2D perovskites, we analyze the interrelated causes and propose rational solutions to these two issues. The scalability issue is scrutinized from the structures of the born inks and the ended films. The efficiency issue is investigated from the structures of the phase landscape and the lattice anharmonicity. Finally, the collective and fine moiety effect for material structure, the state-of-the-art computational methodologies, as well as the machine-learning-based diagnosis are discussed. We hope this Perspective can accelerate the roadmap for building 2D perovskite PV fab.