Sellers, IanSourabh, Shashi2023-05-052023-05-052023-05https://shareok.org/handle/11244/337551Metal halide perovskites are a promising class of solution-based semiconductors with significant potential for optoelectronic devices, including hot carrier solar cells that are proposed to achieve higher efficiency than conventional solar cells. These materials possess high light absorption coefficients, long carrier diffusion lengths, and high defect tolerance, which leads to high power conversion efficiencies in solar cells. However, the intrinsic material instability of perovskite-based solar cells limits their performance. Understanding the carrier dynamics and stability of the material is critical to the development of solar cell physics, particularly in the case of hot carrier solar cells, as excited carriers with energy greater than the bandgap energy can potentially generate higher voltage and current than traditional solar cells. Unfortunately, these hot carriers also tend to rapidly lose their energy through carrier-phonon scattering, resulting in poor energy conversion. Perovskites have shown significant potential for hot carrier solar cells in recent years due to their slow carrier cooling rate. However, a better understanding of carrier dynamics is critical for developing efficient perovskite-based solar cells. The effect of changing the different components of perovskite compounds was studied in a series of metal halide perovskites with varying optical properties using temperature-dependent photoluminescence, power-dependent photoluminescence, and ultrafast transient absorption techniques to investigate the carrier dynamics. The results suggest that the slow cooling of carriers in metal-halide perovskites results from the intrinsic low thermal conductivity of all metal-halide perovskites. This finding indicates that the phonon energy, exciton binding energy, and interaction strength have little effect on the cooling of carriers. This study provides valuable insights into the fundamental understanding of carrier dynamics in perovskite-based solar cells, which can guide the development of more efficient and stable devices. In addition we also studied the presence of hot carriers in a stable metal halide perovskite system under steady-state conditions. The results showed clear evidence of hot carriers in the device, but their behavior was strongly dependent on temperature and competition with photo-induced halide segregation. These findings provide valuable insights into the behavior of hot carriers in metal halide perovskite devices for the development of more efficient and stable hot carrier solar cells. Finally, our study on the 2D Ruddlesden-Popper perovskite (EPEA)2PbI4 using temperature and power dependent photoluminescence and transient absorption spectroscopy showed the presence of multiple excitonic complexes and carrier redistribution mediated by power and/or temperature. Moreover, we observed extremely long-lived dark states in transient absorption, which play a significant role in the photoluminescence and absorption dynamics of (EPEA)2PbI4. These findings contribute to our understanding of perovskite material behavior and could aid in the development of more efficient optoelectronic devices.Physics, Optics.Physics, Condensed Matter.Engineering, Materials Science.Energy.