Harnessing Narrow and Stable Luminescence from Silicon Quantum Dots

Abstract

Luminescent silicon quantum dots (SiQDs) are attractive nanoparticles due to the utilization of non-toxic and earth-abundant silicon. Despite these advantages, challenges in optimizing their optical properties, particularly broad luminescence bandwidths and photostability, persist. This thesis embarks on a comprehensive exploration employing a multidisciplinary approach to overcome these obstacles and unlock the full potential of SiQDs for optical applications. SiQD-based Fabry-Pérot (FP) optical cavities were first explored to narrow the emission bandwidths. Chapter 2 introduces optically driven FP resonators of SiQD-polymer hybrids. This strategy remarkably reduced the photoluminescence (PL) linewidths and demonstrated tunability through variations in nanoparticle size, polymer matrix, and active layer thickness. Furthermore, a significant milestone has been reached with the fabrication of a flexible device. Building on this foundation, Chapter 3 expands the exploration into electrically driven systems and presents SiQD-based cavity light-emitting diodes (SiQD-cLEDs). Beyond developing external structure, Chapter 4 explored the impact of materials' internal structure. The study employed a combination of techniques to investigate the influence of an amorphous silicon (a-Si) layer on SiQD PL under prolonged UV irradiation. A comparison between SiQDs with thick a-Si shells, and those without, reveals nuanced differences in photoluminescence quantum yield (PLQY) after extended exposure. In conclusion, this thesis represents a significant multidisciplinary effort to address challenges in harnessing the SiQDs luminescence. Through the exploration of external and internal structures, these contributions push the boundaries of SiQDs and pave the way for future advancements in light-emitting technologies.