Solution-processed organometallic perovskite based solar cells have emerged as a promising thin-film photovoltaic technology. There have been new reports on the photo-stability of such devices, attributing the hysteresis and performance degradation to various phenomena, including photo-degradation and fast self-healing of the photocurrent in large grain perovskite solar cells of the 3D methyl ammonium (MA) lead iodide materials under constant illumination.[1] The polaronic picture proposed recently is related to contributions from both the inorganic and the organic parts of the material.[2] Layered perovskites obtained by the same growth procedure recently report a record photovoltaic efficiency of 12.52 % with no hysteresis, more than two times higher than previously reported values. [3] Intrinsic quantum and dielectric carrier confinements,[4] and protection afforded by the organic inner barriers in the 2D Ruddlesden-Popper phases, may explain their exceptional photostability under standard illumination as well as humidity resistance over 2000 hours.[3] References [1] W. Nie et al, Nature Comm. (2016) [2] J. Even et al, J. Nanoscale (2016); A. Neukirch et al, Nanoletters (2016) [3] H. Tsai et al, Nature (2016) [4] J. Even et al, Phys. Rev. B (2012), ChemPhysChem (2014); D. Sapori et al, Nanoscale (2016)