低能隙高分子及金屬高分子材料於總體異質接面太陽能電池之合成與應用

Abstract

本論文的主要目的是研究具有電子予體及受體的聚合物及含金屬聚合物，在異質結太陽能電池中的性質研究。論文首先介紹，聚合物太陽能電池的發展歷程，並做個總結。 在第二章中，描述了一系列聚合物設計概念、合成方法及應用在聚合物太陽能電池（PSC）中的效果，這些聚合物主要是由可溶性的phenothiazine做為電子予體，和各種 benzodiazole (如:benzothiadiazole，benzoselenodiazole和benzoxadiazole)做為電子受體，以及夾在中間的hexyl-thiophene所組成。這些低能隙（LBG型）聚合物具有廣泛的吸收範圍(300-750 nm)，光學能隙在1.80-1.93 eV之間，且HOMO（-5.38至-5.47 eV）和LUMO（-3.47至-3.60 eV）能階均在LBG聚合物的理想範圍內。在PSC裝置應用中，以benzothiadiazole為分子內電子受體的聚合物，以重量比1:4混合PC71BM ( [6,6]-phenyl-C71-butyric acid methyl ester)時，所得光電轉換效率1.20％，為所有聚合物中最佳，其開路電壓0.75 V、短路電流值4.60 mA/cm2時、填充因子35.0％。 在第三章中，我們描述一系列含cyclopentadithiophene和dithienosilole的β-cyano-thiophenevinylene-substituted聚合物的設計概念，合成方法和性質分析。並探討橋接原子（C和Si）和cyano-vinylene基團在熱，光，電化學，電荷傳輸和光伏效應等性質上造成的影響。此類LBG聚合物具有廣闊的吸收光譜和理想的HOMO（約 -5.30 eV）和LUMO（約 -3.60 eV）的能階，並具有相當高的hole mobility (9.82×10-4 cm2/Vs)。PSC裝置應用中，一含有dithienosilole之聚合物，混合 PC71BM（1:2 w/w）表現出最佳的功率轉換效率為 2.25％，光源為ＡＭ 1.5下，100 mW/cm2。 在第四章中，描述合成一系列以benzodiazole為核心的bisterpyridine，利用螯合金屬原子形成的含ＲuII聚合物。並探討聚合物中電子予體和受體的相互作用，以及熱，光，電和光伏效應等性質。由於其廣泛的吸收光譜範圍金屬，嘗試應用於BHJ太陽能電池設備中。混合PC61BM（1:1 w/w）作為電子受體表現出高短路電流（Jsc）。所得的最大光電轉換效率（PCE）高達 0.45％，開路電壓 = 0.61 eV，短路電流 = 2.18 mA/cm2，FF = 34.1％（AM 1.5，100 mW/cm2）。因此證明這種新穎的共軛高分子電解質，相較普遍的polythioene，同樣可在ＢＨＪ裝置中，作為供應電子的主動層。

The main objective of this dissertation is to study the performance of polymer bulk heterojunction solar cell involving conjugated donor-acceptor polymers/metallo-polymers as electron donors. In the introduction of this thesis, we gave an explanation on the historical evolution of polymer solar cells, and summarized the literature in the recent years. In the second chapter, we describe the design, synthesis, and polymer solar cells (PSC) fabrication of a series of soluble donor-acceptor conjugated polymers comprising of phenothiazine donor and various benzodiazole acceptors (i.e., benzothiadiazole, benzoselenodiazole, and benzoxadiazole) sandwiched between hexyl-thiophene. These low band-gap (LBG) polymers demonstrated broad absorption in the region of 300-750 nm with optical band gaps of 1.80-1.93 eV. Both highest occupied molecular orbital (HOMO) (-5.38 to -5.47 eV) and lowest unoccupied molecular orbital (LUMO) (-3.47 to -3.60 eV) energy levels of the LBG polymers were within the desirable range of ideal energy levels. The best performance of the PSC device was obtained by using one of the polymers containing benzothiadiazole acceptor at the core and [6,6]-phenyl-C71-butyric acid methyl ester (PC71BM) in the weight ratio of 1:4, and a PCE value of 1.20%, an open-circuit voltage (Voc) value of 0.75 V, a short-circuit current (Jsc) value of 4.60 mA/cm2, and a fill factor (FF) value of 35.0% were achieved. In the third chapter, we describe the design, synthesis, and characterization of □-cyano-thiophenevinylene-substituted polymers containing cyclopentadithiophene and dithienosilole units. The effects of the bridged atoms (C and Si) and cyano-vinylene groups on their thermal, optical, electrochemical, charge transporting,and photovoltaic properties were investigated. Both LBG polymers had broad absorption spectra with ideal HOMO (ca. -5.30 eV) and LUMO (ca. -3.60 eV) levels and possessed hole mobilities as high as 9.82 □ 10-4 cm2/Vs. The PSC device based on one of the polymers containing dithienosilole moiety with PC71BM (1:2 w/w) exhibited a best power conversion efficiency of 2.25% under AM 1.5, 100 mW/cm2. In the fourth chapter, synthesis, and characterization of a series of π-conjugated bis-terpyridyl ligands bearing various benzodiazole cores and their corresponding main-chain RuII metallo-polymers were described. The effects of electron donor and acceptor interactions on their thermal, optical, electrochemical, and photovoltaic properties were investigated. Due to the broad sensitization areas of the metallo-polymers, their BHJ solar cell devices containing [6,6]-phenyl C61 butyric acid methyl ester (PC61BM) as an electron acceptor exhibited a high short-circuit current (Jsc). An optimum PVC device based on the blended polymer with PCBM in 1:1 (w/w) achieved the maximum power conversion efficiency (PCE) value up to 0.45 %, with Voc = 0.61 V, Jsc = 2.18 mA/cm2, and FF = 34.1 % (under AM 1.5 G 100 mW/cm2), which demonstrated a novel family of conjugated polyelectrolytes with the highest PCE value comparable with BHJ solar cells fabricated from ionic polythiophene and C60.