Static and Dynamics Evolution of Charge-carriers in Shape Engineered Metal Halide Perovskite Nanocrystals

Metal halide perovskites (MHPs) nanocrystals (NCs) with their unique structure and exotic properties, emerged as promising and potential material for highly efficient and low costing photovoltaics and optoelectronic applications. For their wide and diverse applications, it is desirable to engineer and tune their properties, which is achieved previously via cation-anion exchange, doping and variation in size. Herein we study the photo-physics of CsPbBr₃ NCs by engineering their shape from usual cubic to rhombic-dodecahedrons and rhombicuboctahedron by steady state and time resolved spectroscopy. In our analysis we observe a remarkably contrasting behaviour of dynamic Burstein-Moss effect (BME) and amplified spontaneous emission (ASE). The BME is observed in the cubic and rhombic-dodecahedrons NCs with shift 24 and 20 meV respectively, on the other hand ASE appeared only in rhombicuboctahedron NCs.  Further it is observed that second-order decay is the major channel for carrier recombination with the rate of 3.68×10^-10, 3.65×10^-10 and 2.03×10^-10 cm³ s^-1 in cubic, rhombic-dodecahedrons and rhombicuboctahedron. These results offer insights into intrinsic photophysics in MHPs with direct implications for photovoltaic and optoelectronic applications by engineering shape of NCs.