Document Type



Doctor of Philosophy (PhD)



First Advisor's Name

Hebin Li

First Advisor's Committee Title

Committee chair

Second Advisor's Name

Xuewen Wang

Second Advisor's Committee Title

Committee member

Third Advisor's Name

Yifu Zhu

Third Advisor's Committee Title

Committee member

Fourth Advisor's Name

Jessica Ramella-Roman

Fourth Advisor's Committee Title

Committee member


spectroscopy, quantum materials, ultrafast dynamics, hybrid perovskites

Date of Defense



Since the rise of the concept of quantum materials (QM), these materials described as many-body quantum systems (interacting atoms, molecules, or electrons) have been suitable for many optoelectronic and quantum applications. Additionally, there has been significant interest in the research of QM to understand the underlying physics behind their extraordinary optical properties. Examples of QM are ultracold atoms, layered 2D semiconductors, supramolecular materials, and more. In 2012, a high energy conversion efficiency of over 10% was reported for the first time for metal-halide perovskite (MHP) solar cells, opening a new era for photovoltaics research. The reported efficiencies have been improved to 22.7% over the years. Additionally, these exceptional semiconductor MHP materials are also promising candidates for the new generation of optoelectronics. This dissertation focuses on studying many-body interactions and their dynamics of MHP methylammonium lead iodide (MAPI) CH3NH3PbI3 thin film materials at room temperature.

In this work, I utilized cutting-edge optical spectroscopies techniques to study ultrafast dynamics of photoexcited electron-holes pairs in MAPI perovskites films. I first performed steady-state spectroscopic measurements to characterize the sample, then implemented optical 2D coherent spectroscopy in the nonlinear geometry to probe the ultrafast dynamics. My experiment revealed many-body couplings and ultrafast dynamics of free-carrier and exciton resonances that coexist for a few hundreds of femtoseconds. According to the results of the 2DCS experiments, the coupling and dynamics of the featured resonances studies were divided into short time (few femtoseconds) and longtime dynamics. The data revealed the charge-carrier relaxation dynamics after the excitation of the sample in terms of thermalization, cooling, exciton dissociation, and many-body effects. Furthermore, those dynamics showed dependence on the excitation control variables, such as wavelength excitation and photoexcited carrier density generated.







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