Preparation Methods Of Optical Micro-and Nano-structures And Applied Research

Following the developments of wave-optics and nanotechnology, research on micro-and nano-photonic structures has made significant progress and become one of the main topics in photonics. Nowadays, most researchers are aiming at the controlling of light transportation, absorption and emission properties through structural designs. Though the investigations of micro- and nano-photonic structures have been continued about two decades, there are still many intractable unsolved problems, together with challenges. For instance, most fabrication processes of micro- and nano-structures require expensive equipments and suffer from the disadvantage of being time-consuming. And the optical response of conventional structures is determined by their structural parameters and remains unalterable once fabricated. It is still difficult to apply the various fancy properties of micro- and nano-photonic structures in the OLED and thin-film solar cell industries which are more and more important because of the energy crisis nowadays. In order to solve these problems partly, we divided this thesis into five chapters to discuss and demonstrate some solutions.In Chapter One, we will give an introduction of the properties and applications of current micro- and nano-photonic structures, as well as a review of the history and recent breakthroughs.In Chapter Two, we will discuss the fabrication processes, the experimental measurements and theoretical simulation methods, which are employed in our group for the research in this realm. We will also give some examples of our recently fabricated micro- and nano-photonic structures. By combining with the self-assembly, electrochemical deposition and nanoimprint technologies, we can fabricate micro- and nano-structures which are low-cost, high-profile and with large areas.In Chapter Three, we will describe the fabrication method and potential applications of our newly achieved plasmonic structure which has active tunable properties. By introducing a flexible and elastic substrate, we can tune the structural parameters by external force and control the optical response. The wavelength shift of our structure can be as large as 47 nm. After releasing from stretching under more than 50% strain, the original structure can be restored.In Chapter Four, we will discuss some results about surface plasmon enhanced photoluminescence of OLED materials. Photon induced emission of phosphorescence material has a 4-times overall enhancement. A 40-times enhancement in emission is observed because of the stronger surface plasmon mode. The above results will lead to a broader photoemission spectrum of organic phosphorescence materials.Chapter Five will discuss the enhanced efficiency of our newly synthesized low-bandgap thin-film organic solar cell which is embedded with a sub-wavelength grating. We strengthen the absorbance and fill factor of patterned devices, which result in an increment of PCE up to 30%.