2D metal halide perovskites (MHPs) are widely investigated for their possible applications in several fields ranging from photovoltaics and photodetection to photocatalysis. From a structural point of view, both Ruddlesden-Popper and Dion-Jacobson families, of general formula A′2An-1MnX3n+1 and A′An-1MnX3n+1, respectively (where A′ and A= organic cations and n = number of staggered inorganic layers made of metal M and halide X), can be seen as composed by inorganic slabs with octahedrally coordinated metal ions (usually Pb), separated by ammonium organic ligands coordinated to the halides of the octahedra. One of the most appealing characteristics of 2D MHPs is their vast chemical (and in turn structural) tunability which can be modulated by changing the organic spacer, the central atom, and the halide. The database of the actually known 2D perovskites can be found in ref. 7. Lead-based 2D perovskites reported so far are close to 700 compositions, followed by tin (79) and finally germanium (2). On the other hand, the recent interest in exploring novel lead-free phases, triggered by the high toxicity of lead which will strongly limit the real use of any material containing this element, requires to significantly expand the plethora of lead-free 2D perovskites. In this context, tin based materials, as mentioned above, have received significant attention in recent years, being this element a quite straightforward alternative to lead based on its electronic structure. However, Ge-containing 2D or even 3D perovskites have been very scarcely considered in the current literature even though some encouraging and interesting properties have been demonstrated in several applicative fields. Such lack of investigation strongly limits the establishment of solid structure-property correlation in Gebased perovskites which is a pre-requisite to design optimized and novel materials. We recently tried to fill this gap by computationally and experimentally exploring a series of germanium 2D MHPs including aromatic monoammonium cations clarifying the role of different structural distortion parameters on the optical properties. Such work allowed us, for example, to further design air and water stable 2D Ge perovskites for photocatalytic applications or to modulate a broad-band emission through external pressure application. In order to provide novel compositions and understanding the role of metal nature and halide alloying on the structural and optical properties of low-dimensional perovskites, we report here the investigation of a novel series of 2D Ge-containing MHPs including decylammonium (DA) as organic spacer.