@misc{9250175,
  abstract     = {{Quasi-two-dimensional (quasi-2D) metal halide perovskites (MHPs) are important low-dimensional semiconductor systems because of their strong excitonic response, tunable emission properties, and improved structural stability compared with conventional three-dimensional (3D) perovskites. In these materials, the inorganic layer thickness and the molecular structure of the organic spacer can modulate quantum confinement, exciton localization, and excited-state relaxation pathways. Understanding these structure-dependent photophysical processes is therefore important for the rational design of perovskite-based optoelectronic materials.

This thesis investigates the emissive-state dynamics of quasi-2D lead halide perovskite single crystals, various quantum well thickness n-pentylammonium lead bromide (n-PAPB)(n=1), n-PAPB(n=2), as well as the organic spacer n-PAPB(n=2), n-butylammonium methylammonium lead bromide (n-BAPB)(n=2), and iso-butylammonium methylammonium lead bromide (iso-BAPB)(n=2)). Steady-state absorption spectroscopy, photoluminescence (PL) spectroscopy, temperature-dependent PL spectroscopy, time-resolved photoluminescence (TRPL), and transient absorption (TA) spectroscopy were used to examine their optical properties and excited-state dynamics.

The absorption and PL spectra suggest the coexistence of multiple quasi-2D domains, likely dominated by n=1-3 phases. Excitation intensity-dependent PL measurements show nearly linear intensity scaling with excitation power, which can be attributed to the dominated excitonic radiative recombination under the investigated excitation conditions. Temperature-dependent PL measurements reveal pronounced electron-phonon interactions that influence the charge carrier recombination at the emissive states. The extracted exciton binding energies are approximately 84-110 meV, indicating strongly localized excitonic states in these quasi-2D structures. Linewidth broadening analysis further suggests coupling between excitons and longitudinal optical phonons. TA spectroscopy indicates ultrafast charge carrier relaxation followed by the formation of long-lived localized excited states.

Overall, this work shows that both inorganic layer thickness and spacer molecular structure are closely correlated with the excited-state dynamics of quasi-2D perovskites. The results provide insight into structure-dependent exciton localization, carrier-phonon interactions, and emissive-state relaxation processes in layered perovskite systems.

Keywords: quasi-2D perovskites; lead halide perovskites; photoluminescence; transient absorption; electron-phonon coupling.}},
  author       = {{Gu, Chenyang}},
  language     = {{eng}},
  note         = {{Student Paper}},
  title        = {{Emissive State Dynamics of Quasi-2D Lead Halide Perovskite Single Crystals}},
  year         = {{2026}},
}