The research on hybrid organic-inorganic perovskite solar cells is growing rapidly with multiple facets nowadays. Efficiencies for these cells have been rising at a phenomenal speed with a certified value over 20%. A rich variety of fabrication methods have been reported with the aim towards low-cost large-scale production, especially focusing on robust deposition methods and stability of the solar cell. An increasing broad types of compositions are being investigated. There is a need to clarify optimal preparation methods, such as precursors compositions and preparation routes. In addition, the hybrid organic–inorganic perovskite materials display a range of fascinating properties that support the extraordinary photovoltaic performance. One obtains fast transport, that could be band-like or polaronic; many reports show a low density of traps; large luminescence efficiency is obtained; recombination rate is affected by contacts; the materials show clear ionic transport that impacts the interface characteristics and influences hysteresis behavior… In summary, despite exciting advances in the field, the principles of photovoltaic and photophysical operation are not clear yet in the perovskite photovoltaic devices. A number of key issues hindering further developments need be investigated thoroughly and solved. This symposium will focus on the key issues and phenomena that are at the frontier of understanding and materials development in perovskite solar cells, including cells film/single crystal growth, chemistry of the materials, lead-free perovskites, surfaces/interfaces, hysteresis, doping, photophysics, instability and fundamental and devices modeling. Researchers developing novel analytical/characterization techniques that are suitable to study perovskite materials/devices are encouraged to submit their works to this symposium. This symposium hopes to become a forum for researchers coming from diverse disciplines to share their research findings and views. Such an interdisciplinary collective approach is particularly vital to establish perovskite solar cells as viable technology. A deepened understanding of these key issues is expected to greatly help assess the true potential of perovskite solar cells under practical considerations, which in the long run will ensure the field to grow in a sustainable manner.