Cd-Rich Alloyed CsPb_1-xCd_xBr₃ Perovskite Nanorods with Tunable Blue Emission and Fermi Levels Fabricated through Crystal Phase Engineering

One-dimensional semiconductor nanostructures have already been used for a variety of optoelectronic applications. Metal halide perovskites have emerged in recent years as promising high-performance optoelectronic materials, but reports on 1D nanorods (NRs) of all-inorganic halide perovskites are still scarce. This work demonstrates a synthetic strategy toward cesium-based inorganic perovskite NRs by exploiting composition-controlled crystal phase engineering. It is accomplished for Cd-rich mixed-cation CsPb_1-xCd_xBr₃ nanocrystals, where the initial 1D hexagonal perovskite phase drives the growth of the 1D NRs, as supported by first-principles calculations. The band gaps of the resulting NRs are tunable by varying the Cd-content, and the highly uniform CsPb_0.08Cd_0.92Br₃ NRs (with an average length of 84 nm and width of 16 nm) exhibit a true blue-color emission centered at 460 nm, with a high quantum yield of 48%. Moreover, this work also demonstrates the tunability of the Fermi levels in the films made of CsPb_1-xCd_xBr₃ alloyed nanocrystals, where samples with highest Cd content show an increase of the electron concentration and a related increase in the conductivity.