Organometal　lead　halides　perovskites　are　promising　solar　cells　material　due　to　their　outstanding　properties　such　as　tuneable　bandgap,　impressive　tolerance　to　defects,　long　exciton　diffusion　length,　high　carrier　mobility　and　absorption　coefficient.　Up　to　now,　the　organometal　lead　halides　based　solar　cells　(PSCs)　have　demonstrated　impressive　power　conversion　efficiency　reaching　25.2%　(not　stabilised).　However,　their　operating　life-times　are　limited　due　to　degradation　of　the　organic　components　under　some　environmental　conditions.　Therefore,　researchers　have　focused　their　interest　on　the　all　inorganic　perovskite;　especially　on　the　caesium　lead　triiodide　perovskite　(CsPbI3)　which　exhibits　a　better　compositional　and　chemical　stability.　Nevertheless,　the　phase　instability　of　the　black　phase　of　this　material　constitutes　its　main　limitation　for　its　use　in　the　solar　cell　devices　production.　This　review　aims　to　present　the　most　impactful　research　giving　insights　on　the　factors　that　may　cause　the　instability　of　all-inorganic　lead　halide　perovskite　materials,　as　well　as　the　instability　of　the　whole　device.　In　addition　to　deposition　methods,　the　composition,　structure　and　optical　properties　of　inorganic　perovskite　materials　have　also　been　presented.　Furthermore,　this　review　highlights　the　different　strategies　used　in　order　to　improve　the　phase　stability　of　caesium　lead　halide　perovskite　material　through　either　engineering　on　the　material　structure　or　the　fabrication　method.