Design, Synthesis and Investigation of Small-Molecule Materials for Organic Solar Cells

在各式各樣的再生能源之中，具有較低廉的建置成本、輕量化的元件、材料多樣性以及可撓曲等優點的有機太陽能電池 (OSCs) 是很受到矚目的新科技，致使許多研究團隊致力於開發新型元件架構與新穎的有機材料，近年來在高分子有機太陽能電池以及小分子有機太陽能電池上都有不錯的元件效率表現。 在本論文中敘述了我在設計與合成AADAA和DAA架構的小分子有機太陽能電池染料的成果，研究分子結構、物理性質以及元件效率表現之間的關係。論文架構如下，第一章介紹有機太陽能電池原理、分子設計策略以及至今最先進應用於有機太陽能電池的小分子和高分子電子予體材料；第二章中我們為了濕製程太陽能電池合成出以雙噻吩并噻咯、雙噻吩并環戊二烯與雙噻吩并苯為中心之AADAA架構的染料，其中CPDT-T1染料達到了0.80%效率。在第三章中，我們增強AADAA染料的拉電子基，合成出了八個AADAA結構的染料，將HOMO與LUMO能階一併拉低的過程中，提升了蒸鍍製成元件的效率表現，其中CPDTBFC可以達到4.94%。在第四章中敘述具有推電子性質的二芳胺接上強拉電子基團thiazolidenemalononitrile，合成了一系列DAA架構的染料，而這些分子的電洞傳導率與分子間作用力息息相關，而在不具有純donor層的PMHJ元件架構下，DPPT效率可以達到3.52%。Among the various solar energy resources, organic solar cells (OSCs) are attracted attention of new technology owing to their advantageous features such as, cheaper manufacturing cost, light-weight, material diversity and mechanical flexibility, that render the interest of many research groups to develop such novel organic materials to design new device configurations. Recently, organic polymer solar cell and small-molecule organic solar cell both show fruitful device performance. This dissertation describes my research effort in the design and synthesis of small-molecule materials with DAA and AADAA molecular configuration for OSCs followed by investigation of molecular structure to evaluate structure-property relationships, physical properties and device performance. The thesis is divided into four chapters and is organized as follow. Chapter 1 provides an introduction of basic principle of organic solar cell, the strategy of molecular design, and a short summary of state-of-the-art of small-molecule and polymer electronic donor materials for OSCs. In chapter 2, we synthesized silolo [3,2-b:4,5-b''] dithiophene, cyclopenta[1,2-b:5,4-b'']dithiophene, and benzo [1,2-b:4,5-b''] dithiophene-based AADAA structure organic dyes for solution process solar cell, and CPDT-T1 exhibited 0.80% efficiency. In chapter 3, we synthesized eight organic dyes with AADAA structure having variable electron withdrawing ability. The lowering of both HOMO and LUMO energy level cause enhanced device performance of vacuum-deposited organic solar cells, and thus CPDTBFC yielded 4.94% efficiency. In chapter 4, we synthesized a series of electron withdrawing thiazolidenemalononitrile-based DAA structure dyes with different diarylamine functionalities. Hole mobility of these compounds is found to be strongly dependent on the various intermolecular interactions. DPPT-based device has 3.52% efficiency of a PMHJ device without the thin donor layer