固態聚(3-己烷噻吩)在外加電場效應下之光學性質與激發動力學之研究

Abstract

於本論文中，將藉由電場引致吸收光譜、電場引致螢光光譜、電場引致螢光-激發光譜與電場引致螢光生命週期光譜針對P3HT高分子材料薄膜之光學性質與激發緩解動力學機制作一系列的探討。 第一部分為探討P3HT高分子材料嵌入於二氧化鈦奈米晶體基材及PMMA高分子材料上的電致吸收光譜來了解其光譜精細結構及探討固態晶體當中激子的史塔克效應。由於在室溫之下作量測往往有複雜之光譜展寬，因而正常情況下無法直接由吸收光譜獲得激子吸收峰以及相干電子電洞對之躍遷譜線，透過對電致吸收光譜作二次微分並以高斯函數擬合，能夠做到對原光譜的拆解及擬合，並做為精確測定分子偶極矩變化與極化率變化量之新穎測定方法。 第二部分為P3HT高分子及其混和材料激態緩解動力學。藉由量測材料之電場引致螢光光譜及電場引致螢光-激發光譜，並以高斯函數擬合，計算出施加電場與未施加電場之螢光量子產率比例。其次透過量測材料之電場引致螢光生命週期光譜，我們能夠得到材料的螢光生命週期，並配合施加電場與未施加電場之螢光量子產率比例計算出螢光緩解電子轉移常數及螢光緩解輻射常數。最後利用螢光生命週期與螢光緩解輻射常數計算出P3HT高分子材料嵌入於不同材料間的螢光量子產率。

Electro-absorption (EA) measurement、electrophotoluinescence (E-PL) measuremen、electrophotoluminescence-excitation (E-PL-Ex) measurementand and electrophotoluminescence decay measurement were carried out to investigate optical property and the relaxation excitation dynamics of P3HT polymer embedded in a PMMA and P3HT solid film. By the EA measurements, the field-induced spectral change is obtained for P3HT under any condition. If we differentiate EA spectrum twice , the hidden peak can be resolved from second derivatives components of spectrum which is simulated by using Gaussian function. Based on the results, the exciton band has been confirmed and separated from the direct band-to-band transition. By analyzing the Stark shift of the optical transition, we can obtain the change in dipole moment (△μ) and the change in polarizability (△α) of materials following absorption. Electric field effect on excitation relaxation dynamics both of P3HT solid film contacted with TiO2 on Sb2S3 solid film and of P3HT embedded in a PMMA film have been also examined. We could obtain the magnitude of the field-induced change in fluorescence quantum yield relative to the total fluorescence quantum yield (ΔIPL/IPL) of P3HT under different conditions by using E-PL and E-PL-Ex spectrum. Furthermore, we could obtain the fluorescence lifetime of P3HT under different sample condition both in the absence and in the presence of electric field. In the result, we could calculate the electron transfer rate and radiative rate constant withΔIPL/IPL and fluorescence lifetime. Also, We could calculate the quantum yield at zero field and in the presence of electric field using fluorescence lifetime and radiative rate constant of P3HT under different sample condition.