Optical characterisation of AAO/CsPbBr3 perovskite nanocomposites

Sammanfattning: Direct bandgap metal lead halide perovskites offer promising optoelectronic properties desirable in a wide range of applications including photodetection. However, the incomplete and poor understanding of the photophysical processes taking place in these materials, along with their poor stability, is the bottleneck for optimisation and further development of metal halide perovskite devices. In this work, we study all-inorganic CsPbBr3 perovkite nanowires embedded in anodized aluminium oxide (AAO) template where samples with templates of different pore sizes, ranging from 30 - 360 nm, are optically characterised with photoluminescence spectroscopic techniques. Steady-state photoluminescence spectroscopy reveals a blue-shift in the emission wavelength with decreasing nanowire diameter beyond quantum confinement. The origin of such an effect remains ambiguous, however, the shift in wavelength is attributed to possible strain effects induced by the AAO matrix on the lattice structure of the nanowires. Time-correlated single photon counting unveils different charge carrier dynamics for smaller nanowire diameter, 30 - 170 nm, and larger nanowire diameter 250 - 360 nm samples. Here the longer charge carrier decay times of samples with smaller nanowire diameter suggest a trap-mediated radiative decay dynamics.