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B-site doping with various metal ions in α-CsPbI3 has been proven to be a potential approach in bringing phase stability to these nanocrystals. However, while the doping of various homovalent ions in replacing Pb­(II) has been extensively studied, heterovalent doping was observed to be limited. To understand the impact of heterovalent doping, Sb­(III) was chosen here as an effective dopant for occupying the Pb­(II) position in CsPbI3 nanocrystals. Importantly, it was observed that insertion of Sb­(III) also stabilized the crystal phase of these red-emitting nanocrystals, but only with limited doping. However, with more intake, the cube shape turned to platelet and therefore also reduced the stability. Details of the insights of formation of these doped nanostructures are investigated, and further, these were implemented for photovoltaic application and comparable efficiency was recorded.

Red emitting α-CsPbI 3 nanocrystals are highly phase sensitive to ambient exposure, and B-site doping with suitable cations is adopted as one of the most feasible approaches for their phase stability. There are several reports herein: Ni(II) ions having the smallest transition metal Shannon radii were explored for doping in these nanocrystals. This successfully stabilized the cubic phase and retained the intense emission of nanocrystals for nearly 2 months. Being the smallest ion, the halide octahedra in the perovskite lattice were expected to provide high restraint ability toward δ-CsPbI 3 . Comparing with postsynthesis iodide treatments, the importance of doping in high temperature reaction was discussed. Finally, these doped nanocrystals were explored for photovoltaic devices and showed comparable efficiency (9.1%) to different other similar doped nanocrystals. Hence, the finding reported here is a step forward for understanding the insights of phase stability of α-CsPbI 3 perovskite nanocrystals.

Grain boundaries in bulk perovskite films are considered as giant trapping sites for photo-generated carriers. Surface engineering via inorganic perovskite quantum dots has been employed for creating monolithically grained, pin-hole free perovskite films.