二六族半導體奈米材料之製備與其在有機光電元件之應用

Abstract

本研究內容可分為兩大主軸: 第一主要探討半導體奈米材料之製備與應用，探討具不同發光波長量子點之製備、特性鑑定與其於有機發光二極體之應用。第一章介紹無機半導體量子點之發展歷史及文獻回顧，第二章敘述研究方法，第三章則探討應用於發光二極體中所扮演之角色。本研究利用有機無機發光元件之優點，進而以量子點為發光層材料，藉由有機無機混成之方式，利用量子點粒徑調控，以獲得不同發光波長之量子點，進而製作單色光或混合白光發光二極體。 第二研究探討另一種非放光性無機半導體材料之發展歷史與其應用於聚合物太陽能電池中之可行性，同時研究其所扮演之角色與機構。 第四章則介紹以溫度控制方式於ITO電極上生長氧化鋅奈米結構，特殊其山脊結構主要扮演著電子收集與傳遞，使得太陽電池填充因子大幅提升進而增進電池效率。相較於兩階段製備之一維奈米結構或表面再修飾法，此方法可簡單地控制奈米結構，進而可應用於倒結構(inverted)聚合物太陽能電池。 第五章主要介紹非晶相氧化鋅之製備與其應用於聚合物太陽能電池之可行性，並設計與結合不同p型材料，製備出具有良好電性、化學性質、物理性質之中間介面層，進而首次製作與發表高效率(~5.1%)倒結構串接(inverted tandem)太陽能電池。 第六章則總結本論文之研究成果與未來研究目標，本研究已成功將無機半導體材料結合有機電激發光元件，發光量子點取代發光層以增加元件穩定性與光色單一性。另一項研究成果則在於無機奈米結構對於聚合物太陽能電池影響之了解。並結合不同材料P-N材料之特性，進而了解多層聚合物太陽能電池之可行性。

This thesis is divided into two major sections. The first part is being the synthesis and characterization of the quantum dot (QD), followed by the fabrication and character- ization of the resulting QD-LEDs. The fabrication of QD-LEDs consists of synthesizing the semiconductor nanocrystals (NCs) with the desired properties followed by the incorporation of these NCs into PLED based device structures. Chapter 3 introduces the semiconductor CdSe/ZnS and discusses in detail the synthesis, characterization, and properties, as well as how the application CdSe/ZnS QDs into device. The fabrication and EL characterization of a white-emitting hybrid QD-LED by integrating core-shell CdSe/ZnS QDs acting as a yellow emitter and polyfluorenes as the blue emitter in a multilayered structure. The second part is being the synthesis and characterization of the zinc oxide (ZnO) materials, followed by the fabrication of the resulting ZnO based polymer solar cells. Chapters 4 discuss the design of a ZnO nano-ridge structured film that can be used as an electron collection layer in an inverted polymer solar cell. The ZnO nano-ridge structure was formed by a simple sol-gel process using a ramp annealing method. As the solvent slowly evaporated due to the low heating rate, there was sufficient time for the gel particles to structurally relax and pile up, resulting in a very dense and undulated film. This film provided an effective charge selection layer and an increased interfacial area for charge collection. Chapter 5 discusses the study of a highly efficient tandem polymer solar cell with inverted polarity. The optically transparent interlayer, consisting of a molybdenum trioxide (MoO3) layer and an amorphous ZnO, serves as the interconnecting layer facilitating charge recombination between the bottom and top sub-cells. The ZnO layer, prepared by a low temperature process, provides a dense layer for electron collection and a barrier against solvent from dissolving the under layer. The leads to the high photovoltaic performance in both single and tandem inverted solar cells. Under simulated solar illumination of AM 1.5G (100 mWcm-2), the device exhibited a Jsc = 7.8 mAcm-2, Voc = 1.20 V, FF = 0.54, and η = 5.1%. This is the first study reach over 5% in the successful demonstrated in inverted tandem solar cell. Chapter 6 is the achievement and summary for this thesis and future prospects