有機太陽能電池中光場分佈、電流-電壓特性與銀奈米線網絡之分析與模擬

Analysis and Simulation of Optical Field Distribution, Current-Voltage Characteristics and Silver Nanowire Network in Organic Solar Cells

黃正宇

指導教授 ： 林皓武

國立清華大學/工學院/材料科學工程學系/碩士(2013年)

摘要

傳統上，物理方法分為理論和實驗。但隨著電腦運算能力的提升，一種兼具理論與實驗的特性，卻又獨立於外的物理方法，數值模擬，開始蓬勃發展，建立於基本的物理定律，利用電腦模擬在不同情況下之物理現象。本篇研究展示幾種應用於有機薄膜太陽能電池的數值模擬方法。
第一章將介紹有機太陽能電池工作原理與量測技術。第二章與第三章，分別以轉換矩陣法模擬一維層狀結構與以有限時域差分法模擬二三維結構之光學特性。光學模擬能幫助我們在元件製作前設計元件結構且對結構最佳化，或取得一些難以實驗得到的數據，例如光場分佈及激子在有機半導體材料內之擴散長度等。第四章探討元件表現隨入射光強度之變化，並以一簡單的模型對電壓電流量測值做擬合，得到有機太陽能元件中不同再結合機制所佔的比例。第五章以蒙地卡羅法模擬奈米銀線網絡的分佈，評估不同分佈方式對網絡面積覆蓋率及片電阻的影響。最後，總結各章節的模擬結果，並提出未來可能的發展方向。

關鍵字

光場分佈 ； 電流電壓曲線分析 ； 奈米銀線網路 ； 光學模擬 ； 轉換矩陣法 ； 有限時域差分法 ； 載子再結合 ； 蒙地卡羅法

並列摘要

Physics methods commonly can be catagorized as theories and experiments. However, with the advance of computer calculations, a new method called numerical simulation, which has both characteristics of theories and experiments, becomes more and more popular recently. Based on the basic physical laws, physical phenomenon in different conditions can be simulated by computer programs. In this study, we demonstrate the applications of numerical simulation in optoelectronic properties of the organic thin-film solar cells.
In chapter 1, the operation principles and the characteristics of the organic thin-film solar cells are discussed. In chapter 2 and 3, different optical simulation methods are introduced. The transfer matrix method has been used in 1-D simulations, while the finite-difference time-domain method has been use in 2-D and 3-D simulations of optical characteristics of the organic thin-film solar cells. With the help of simulations, the device structures can be designed and further optimized prior to fabrication. We also show that some physical data, such as optical field distributions in the devices and exciton diffusion lengths in the organic semiconductors, which are difficult to be obtained by real-world measurement, can be extracted. In chapter 4, to explore the dominate recombination mechanism in the organic thin-film solar cells, the J-V characteristics under different illumination intensities have been analyzed and fitted with a simple model. In chapter 5, the Monte Carlo method is applied to the simulation of the silver nanowire network. The effect of the nanowire orientation and distribution on the area coverage ratio and the sheet resistance has been studied. In the last chapter, the results of the simulation in each chapter are summarized and the further development directions are presented.

並列關鍵字

Optical Field Distribution ； Current-Voltage Characteristics ； Silver Nanowire Network ； optical simulation ； transfer matrix method ； FDTD ； carrier recombination ； Monte Carlo method

參考文獻

[1] S.R. Cowan, N. Banerji, W.L. Leong, A.J. Heeger, Charge Formation, Recombination, and Sweep-Out Dynamics in Organic Solar Cells, Adv. Funct. Mater. 22,(2012), 1116.

[2] C.J. Brabec, A. Cravino, D. Meissner, N.S. Sariciftci, T. Fromherz, M.T. Rispens, L. Sanchez, J.C. Hummelen, Origin of the Open Circuit Voltage of Plastic Solar Cells, Adv. Funct. Mater. 11,(2001), 374.

[3] M.C. Scharber, D. Mühlbacher, M. Koppe, P. Denk, C. Waldauf, A.J. Heeger, C.J. Brabec, Design Rules for Donors in Bulk-Heterojunction Solar Cells—Towards 10 % Energy-Conversion Efficiency, Adv. Mater. 18,(2006), 789.

[4] V.D. Mihailetchi, P.W.M. Blom, J.C. Hummelen, M.T. Rispens, Cathode dependence of the open-circuit voltage of polymer : fullerene bulk heterojunction solar cells, J. Appl. Phys. 94,(2003), 6849.

[5] S. Gunes, H. Neugebauer, N.S. Sariciftci, Conjugated polymer-based organic solar cells, Chem. Rev. 107,(2007), 1324.