First-principles ultrafast charge carrier dynamics of methylammonium lead halide perovskites

Methylammonium lead halide perovskite semiconductors, MAPbX3 (MA = CH3NH3, X= I, Br, Cl), have become the focus of research efforts in the field of photovoltaics. Investigating processes on a nanoscale level can be achieved through real-time time-dependent density functional theory and Ehrenfest molecular dynamics. In a first-principles work based on real-time time-dependent density-functional theory, we investigate the ultrafast charge-carrier dynamics of MAPbI3. This work also includes ab initio density-functional theory (DFT) calculations on the electronic structure of using state-of-the-art functionals, including HSE06 and GW approximations. The electronic structure results confirm a high localization of the inorganic component of the perovskite near the Fermi level. It was found that the CH3NH3+ cations do not contribute to the optical absorption but instead act as a structural filler and ensure the charge neutrality of the unit cell. The ultrafast dynamics of methylammonium lead halide perovskites (X = I) were analyzed by following the evolution of the charge-carrier population using the formalism of real-time time-dependent densityfunctional theory (TDDFT). The absorption spectrum calculated under the adiabatic local density approximation (ALDA) approach reproduces two high-energy excitations, consistent with experimental results. By irradiating the system with coherent femtosecond pulses at varying intensities, a pronounced intensity-dependent response was observed, manifested through high-harmonic generation. In this way, one can interpret the charge-carrier dynamics in terms of simple estimators, such as the number of excited electrons.

• المؤلف الرئيسي: Cabrera Aguilar, Ariel Moisés (author)
• التنسيق: bachelorThesis
• اللغة: eng
• منشور في: 2023
• الموضوعات: Density functional theory; Ultrafast dynamics; Semiconductores
• الوصول للمادة أونلاين: http://repositorio.yachaytech.edu.ec/handle/123456789/659