CsPbBr3 perovskite NCs are promising materials for applications such as solar cells, lasers, LEDs, and other optoelectronic devices. Studying the photophysical processes and factors that control them is essential to improve such devices' efficiency.
This thesis focuses on how the nano and the microscale morphology affect the excited state dynamics using transient absorption spectroscopy. Nanoscale: We investigated the one-photon linear absorption (OPLA) and two-photon absorption (TPA) properties of NCs with different aspect ratios (AR). We also studied the exciton and biexciton lifetimes and discovered dimensionality independence to their values. The morphology relationship to the optoelectronic properties of CsPbBr3 NCs is still under discovery.
We give a new perspective that can aid in the understanding of such properties by exploring the local field correlation to the TPA coefficient. Microscale: We studied the carrier dynamics in a bi-sized film of DDAB capped CsPbBr3 QDs. We reveal how carrier diffusion happens in the large-sized QDs instead of the small-sized QD due to the strong quantum confinement. Combining the carrier diffusion study with a Monte Carlo simulation on the QDs assembly, we can calculate diffusion lengths of charge carriers. The diffusion length of the DDAB capped shows higher values than the ones for the common capping agents oleylamine and oleic acid. Explaining the higher efficiencies of DDAB capped CsPbBr3 QDs LEDs.
There is no doubt that morphology plays a vital role in designing efficient devices. A deep understanding of nanoscale morphology can help develop new materials with optimized properties. New arrangements in the microscale can beat the electron transfer limitations the current devices face.