Exciton diffusion in two-dimensional metal-halide perovskites

• Autores: Michael Seitz
• Directores de la Tesis: Ferry Prins (dir. tes.), Daniel Congreve (codir. tes.)
• Lectura: En la Universidad Autónoma de Madrid ( España ) en 2021
• Idioma: español
• Tribunal Calificador de la Tesis: Beatriz Hernández Juárez (presid.), Antonio I. Fernández Domínguez (secret.), Naomi Ginsberg (voc.), Ferdinand C. Grozema (voc.), Stéphane Kena Cohen (voc.)
• Programa de doctorado: Programa de Doctorado en Física de la Materia Condensada, Nanociencia y Biofísica por la Universidad Autónoma de Madrid; la Universidad de Murcia y la Universidad de Oviedo
• Materias:
  • Física
• Enlaces
  • Tesis en acceso abierto en: Biblos-e Archivo
• Resumen

  • Metal-halide perovskites have emerged as a promising material platform in many optoelectronic applications such as light harvesting and light emitting applications. Perovskites offer a unique combination of outstanding properties, however, conventional 3D perovskites suffer from rapid degradation when exposed to ambient conditions. Two-dimensional (2D) perovskites, on the other hand, have been shown to have a superior chemical stability and have proven to be one of the most promising strategies to yield a more stable performance. However, the reduced dimensionality of 2D perovskites dramatically affects the charge carrier dynamics in these materials as excitons - electron-hole pairs - become the dominant energy carriers rather than free charges. While there has been an extensive amount of research to understand the charge carrier dynamics in 3D perovskites, our knowledge about the exciton dynamics in 2D perovskites is still limited.

    This thesis strives to close part of this knowledge gap by studying the transport properties of various 2D perovskites. We will discuss the influence of organic-spacer molecules and find that transport is most likely limited due to strong exciton-phonon interactions. Further, we investigate the effect of halide alloying - the most commonly used strategy to change the color of the perovskite materials in, for example, LEDs. Surprisingly, we find that halide alloying can diminish exciton transport and therefore has to be considered for device design. Finally, the impact of trap-states on exciton diffusion will be thoroughly studied. We will provide models to describe trap state-limited exciton transport and show that transient microscopy can be used as an orthogonal method to more conventional optical characterization techniques. The results in this thesis are primarily derived from transient optical microscopy and spectroscopy measurements, and rigorous modeling of exciton transport by solving the diffusion equation and performing Brownian dynamics simulations.