Also the temperature plays an important role: while MAPbI3 has a reported decomposition temperature of 300°C [66], the decomposition to PbI2 at surfaces or grain boundaries has been found to occur at much lower temperatures as 150°C [138] and even 105°C [139]. More worrying, MAPbI3 presents two crystalline phase transition around −111oC and 57°C, from orthorhombic to tetragonal and from tetragonal to cubic, respectively [65, 66, 140]. Regarding the first, the work by Jacobson et al. [141] discarded space applications due to the drastic PCE reduction toward the orthorhombic phase; while also recommended room temperature as the most profitable. On the other hand, considering that under sunny summer days the panels can reach over 80°C, the crystal instability of MAPbX3 (X−Cl, Br, I) has gained the attention of several studies, as summarized by Niu et al. [142].
Anyway, there is still extensive research ongoing to understand the different and dominant PSCs degradation pathways, but clearly it was the moisture possibly the first major factor identified to affect MAPbI3 stability in PSCs [143]. For preventing this, a primary strategy has been focused on the guarding and protecting of the absorber from external assaults by developing specialized functional barrier structures [144].
of surface-adsorbed oxygen, which was not present in meso-TiO2 free devices. On the other hand, J.A. Christians et al. [149] found superior photocurrent stability when substituting spiro-OMeTAD by CuI. Also a tetrathiafulvalene derivative (TTF-1) as HTM was introduced by J. Liu et al. [150] as a stability improver. A more central change in the device architecture was proposed by S. Aharon et al. [151] who obtained best stability with FAPbI3 as absorber material. The role of interface in stability is nicely reviewed in the article by Manspeaker et al. [152].