Colloidal cesium lead halide perovskite (CsPbX3, X = Cl, Br, I) nanocrystals (PNCs) are the most promising photoluminescent inorganic self-assemblies owing to their cutting-edge applications in tandem-solar cell, light-emitting diodes and photo(electro)catalysis. However, these photoluminescent nanocrystals remain far from practical applicability due to their poor ambient stability. Coulombic interaction guided dynamic binding between ammonium ions (of oleylamine) with bromide ions present in crystal lattice and oleate ions (of oleic acid) with lattice's cesium ions falls apart in presence of water molecule, as oleate becomes oleic acid and leaves hydroxide ion. This hydroxide ion readily forms lead hydroxide salt, Pb(OH)2 with crystal's Pb(II) ion. Very recently Ma et al. have elucidated the intricacies of binding water molecules with formamidinium lead iodide (FAPbI3) nanocrystal and demonstrated that its crystal facet {100} is substantially more vulnerable to moisture-induced degradation than facet {111}. To improve the ambient stability of PNCs, doping of metal ions into perovskite crystal is in current focus of research. Metal ion-doped perovskite nanocrystals (M:PNCs) possess unique excellent photostability (PL), narrow spectral widths, and bandgap tunability. Very recently, doping of several alkaline-earth metals (e.g., Mg 2+ , Ca , and Ba 2+ ) into perovskite nanocrystals have been investigated for improvement of photoluminescence quantum yield. Transition metal ions have also been tested as dopants for achieving near-unity photoluminescence quantum yield, band tuning and improving stability. The defect tolerance ability of PNCs remains the foundation behind such doping. However, a greater emphasis on sustainability vis-à-vis Net-Zero carbon emission has also pushed researchers to harness the potential of metal-doped perovskite nanocrystals for photocatalytic applications-such as, green hydrogen production and sustainable fuels/chemicals production by CO2 reduction. Scheme 1: Highlighting the research gap and scope of our work in deciphering facet-directed energy transfer dynamics of transition metal-doped Cesium lead halide perovskite nanocrystal (M:PNC).