Note that, after 10 hours, the PL peak intensities of the n=1 and 2 2D HPs are increased at the expense of those from the 3D-like phases across the compositional space (Figure ). The decreased PL intensity of the 3D-like HPs indicates the temporal degradation of the corresponding crystallites upon ambient exposure during the measurements. The degradation action disintegrates the 3D-like HPs into fragmented building blocks, which are, in turn, merged into n=1 and 2 2D phases. That is, BA offers insufficient ambient stability of the 3D-like HPs, which makes them impractical for PV applications. Essentially, these changes are associated with the degradation action of the quasi-2D HPs, and thus, it is legitimate to assume that such spectral features showing across the quasi-2D HP compositional space are an indicative of the functionality of the spacer cation on the stability of the film matrices; the appreciable spectral changes in the compositional space indicates that the corresponding spacer cation cannot benefit the stability of the quasi-2D HP films.