Abstract: The present invention relates to a new type of low-dimensional hybrid post-perovskites for high efficiency white light emission. More precisely, the invention relates to a one dimensional post-perovskite of formula AaMmXx.yH2O wherein A is a cis- or trans-2,5-dialkylpiperazine derivative bearing C1-C3 linear or branched alkyl groups, M is one or more metal, X one or more halogen, 0<a<5, 1<m<2, 2<x<12, 0<y. The invention also relates to material and luminescent device comprising the same and methods of preparation of the of low-dimensional hybrid post-perovskites.