電洞型低能隙有機小分子之開發與其太陽能電池應用

Abstract

因應全球能源危機及環保意識的抬頭，太陽能電池由於其理論效率高且技術發展較為成熟，成為近年來最受矚目的綠色替代性能源。許多高光電效率轉換之研究顯示，配合新有機分子材料的開發，以其為基底的染料敏化太陽能電池與有機薄膜太陽能電池，因其價格低廉，重量輕與可撓曲性皆優於市場上主流的無機單晶矽太陽能電池，充分顯示此類型有機太陽能電池未來的發展潛能。而太陽能電池元件中的光吸收層，採用有機小分子具有以下的優勢：(1)各批次間性質成份穩定且再現性高；(2) 化學合成法能簡易地改變分子之結構，並調控能階與吸收光譜使之消光係數提高；(3)具有固定分子結構。 本論文的研究主軸，是由設計不同有機分子的化學結構為基礎，探討其不同功能性之化學基團對巨觀材料性質及光電元件效能的影響，來開發高效率有機太陽能電池。在此，第一章將詳細地討論有機結構異構物之間的光物理性質差異以及其應用於染料敏化太陽能電池的元件表現。第二章描述不對稱有機小分子予體材料之設計概念與其蒸鍍型太陽能電池的元件結果。第三章討論應用於濕式製程太陽能電池的不對稱及對稱型小分子骨架與寡聚物材料，包含其結構設計概念、合成、鑑定與光電元件特性。以上的研究工作將有助於開發更多高效率的電洞型低能隙有機小分子，並且系統性客觀地分析化學結構特異性、固態光電性質、元件薄膜製作條件與最終元件效率表現之關聯。

The solar cell has been recognized as a promising future source of affordable renewable energy to address global energy needs and environmental concerns. Consistent improvements in developing organic solar-energy harvesting materials for organic photovoltaics (OPVs) and dye-sensitized solar cells (DSSCs) have been motivated in part with the advantage of low-cost, lightness, and flexibility over conventional inorganic silicon-type counterparts. Significant advancements in organic small-molecule OPVs recently have made them an attractive alternative with the eminent advantages of high batch-to-batch reproducibility, broad and red-shifted absorption in the light-harvesting region and monodispersity with well-defined chemical structures. This dissertation discloses the special chemical-structure considerations needed to realize efficient solar cells, including new organic frameworks for enhancing absorption response and results of multidisciplinary studies ranging from molecular-level chemical-structure to materials science and device engineering. Chapter 1 provides a brief overview to disentangle the regioisomeric effects on electronic features of organic sensitizers for DSSCs. Chapter 2 presents the design principle of an asymmetric framewok for small-molecule donors and their applications in vacuum-deposited OPVs. Chapter 3 comprises the syntheses and characterization of both asymmetric, symmetric small-molecules and oligomeric molecules for solution-processed OPVs. These efforts deal with the judicious design of p-type low-bandgap organic materials and the exploration of structure-property-processing-performance relationship.