Manipulació de la llum en dispositius optoelectrònics mitjançant nanoestructures fotòniques ressonants
- Autores: Pau Molet Bachs
- Directores de la Tesis: Antonio Agustin Mihi Cervello (dir. tes.)
- Lectura: En la Universitat Autònoma de Barcelona ( España ) en 2021
- Idioma: catalán
- Tribunal Calificador de la Tesis: Jordi Martorell Pena (presid.), Gervasi Herranz Casabona (secret.), Esther Alarcón Lladó (voc.)
- Programa de doctorado: Programa de Doctorado en Ciencia de Materiales por la Universidad Autónoma de Barcelona
- Materias:
- Enlaces
- Tesis en acceso abierto en: TDX
- Resumen
Currently, one of the main challenges in light management at the nanoscale is the transition from the laboratory to real applications. Despite the great potential shown by photonic architectures to optically improve the performance of many devices, transitioning into marketable devices is often hampered by the low-throughput and expensive nanofabrication techniques involved. This thesis is devoted to the design and development of subwavelength light managing strategies to improve the light harvesting or out-coupling in solar cells, photodetectors and light emitters while using a scalable nanostructuration such as soft nanoimprint lithography (NIL). This technique has been proven to achieve resolutions down to few tens of nanometers with high fidelity in large areas, being compatible with roll to roll processing. It is also versatile regarding the materials where it can be used, non-invasive, and can be seamlessly introduced in the devices fabrication scheme. With the aid of this technique, we explore a variety of photonic architectures and the different types of resonances sustained, from Brewster modes to Mie resonances, in order to enhance the light-matter interaction with the active layer of the device.
First, we develop a strategy to achieve broadband optimal absorption in ultra-thin semiconductor materials (less than 100 nm thick) for all energies above their bandgap. The interplay of strong interference thin film resonances and photonic crystal modes sustained by a high refractive index nanostructure on a gold film renders the system with a 81% total absorption over a broad spectral range (from 400 to 1500 nm).
Second, we combine soft NIL and chemical vapor deposition to obtain an array of silicon hemispheres on top of a high refractive index dielectric waveguide. We study the Mie resonances supported by the substrate, how these hybridize with the guided modes of the waveguide and how their interaction influences the electromagnetic near field of the metasurface. We further explore the tunability of such resonances with the design parameters of the structure and we demonstrate a potential application of it as a substrate for enhanced photoluminescence.
In the third part of the thesis, we focus on the implementation of 2D photonic structures within the active layer of three different devices to improve performance. In particular we enhance the near infrared (NIR) photon harvesting efficiency in a colloidal quantum dot solar cell (PbS-CQD) and in organic photodetectors (P3HT: PC60BM and PBTTT: PC70BM) and improve the light out coupling from a nanophosphor layer (GdVO4:Eu3+ nanocrystals). We developed photonic systems tailored for each device and provide the complete optical and electronic characterization for each case. The nanostructuration with a 2D periodic arrangement renders the active layers with resonant waveguide properties enhancing its light trapping properties in the targeted spectral ranges, hence demonstrating the possibility to implement photonic schemes within actual devices.
