【摘要】：自從1991年Gr tzel等人報(bào)道了具有簡單結(jié)構(gòu)的染料敏化太陽能電池(DSSCs)的效率高達(dá)7%以來，DSSCs就引起了人們的廣泛關(guān)注。與傳統(tǒng)的硅基半導(dǎo)體太陽能電池相比，DSSCs具有高能量轉(zhuǎn)換效率及低成本等優(yōu)點(diǎn)。實(shí)驗(yàn)上以鋅卟啉類染料為光敏劑的DSSCs的效率已達(dá)到12.3%。然而，由于金屬的價格昂貴，因此限制了DSSCs的大規(guī)模商業(yè)化應(yīng)用。近些年，基于非金屬有機(jī)染料的DSSCs因其低成本、易制備、環(huán)保，同時具有較高的光電轉(zhuǎn)換效率等優(yōu)點(diǎn)而越來越受到人們的重視。光敏染料作為DSSC的重要組成部分，其結(jié)構(gòu)上的微小差異會引起器件性能的顯著不同。但實(shí)驗(yàn)上設(shè)計(jì)合成高效的染料分子仍存面臨巨大挑戰(zhàn)，近年來，，量子化學(xué)方法已成為了揭示染料分子結(jié)構(gòu)與性能之間關(guān)系的可靠的研究手段。 本文主要包括兩部分研究工作： 第一部分： 為了合理解釋二聚噻吩類染料分子結(jié)構(gòu)與性能之間的關(guān)系，采用密度泛函理論(DFT)和含時密度泛函理論(TDDFT)討論了包括紫外-可見吸收光譜、光捕獲效率、電子注入驅(qū)動力、垂直方向偶極矩和電子轉(zhuǎn)移數(shù)目在內(nèi)的一系列影響染料性能的理論參數(shù)．結(jié)果表明，在光捕獲效率和電子注入效率差別不大的情況下，染料分子較低的染料再生效率可導(dǎo)致其短路電流較小;同時，在由光誘導(dǎo)產(chǎn)生的從染料分子轉(zhuǎn)移到半導(dǎo)體的電子數(shù)目以及電子復(fù)合程度相差不大的情況下，染料分子垂直方向上較大的偶極矩則可導(dǎo)致其具有較高的開路電壓． 第二部分： 為了揭示D-D-π-A型染料的結(jié)構(gòu)和性能之間的關(guān)系，本文結(jié)合密度泛函理論（DFT）以及含時密度泛函理論（TDDFT）圍繞染料分子的幾何、電子結(jié)構(gòu)，吸收光譜，電化學(xué)性質(zhì)，電子復(fù)合程度，以及半導(dǎo)體導(dǎo)帶邊緣的移動進(jìn)行討論。結(jié)果表明：相比于常規(guī)經(jīng)典的D-π-A型染料分子，引入額外的給體，即D-D-π-A型雙給體染料，可以改變體系的共軛程度，增加染料的光吸收強(qiáng)度；其中吩噻嗪和二苯胺基等非平面性給體的引入可以使染料吸收光譜紅移，并且顯著的調(diào)節(jié)染料的基態(tài)、激發(fā)態(tài)的氧化電位；反之，咔唑剛性給體的引入則使吸收光譜藍(lán)移，只能微調(diào)染料的基態(tài)、激發(fā)態(tài)的氧化電位。另外，額外給體的引入可以顯著增加染料陽離子空穴-半導(dǎo)體之間的距離，從而抑制注入電子與染料陽離子的復(fù)合；在額外給體中引入雜原子可以使I2聚集在染料外側(cè)，從而降低電解質(zhì)在半導(dǎo)體表面的局域濃度，進(jìn)而減慢注入電子與電解質(zhì)之間的復(fù)合速率。盡管額外給體的引入可以引起導(dǎo)帶移動發(fā)生變化，但是這種變化并不顯著的，可以忽略。計(jì)算結(jié)果表明通過在常規(guī)經(jīng)典的D-π-A型染料上引入額外的電子給體構(gòu)筑D-D-π-A型染料可以有效調(diào)節(jié)染料的光學(xué)、電學(xué)以及電子復(fù)合等各方面性質(zhì)，從而為高性能的染料提供更直觀、清晰的思路。
[Abstract]:Since Gr tzel et al reported that the efficiency of dye-sensitized solar cell (DSSCs) with simple structure is as high as 7% in 1991, DSSCs has attracted extensive attention. Compared with the traditional silicon-based semiconductor solar cells, DSSCs has the advantages of high energy conversion efficiency and low cost. In the experiment, the efficiency of DSSCs with zinc porphyrin dye as photosensitizer has reached 12.3%. However, because of the high price of metals, the large-scale commercial application of DSSCs is limited. In recent years, DSSCs based on non-metallic organic dyes has been paid more and more attention because of its low cost, easy preparation, environmental protection and high photoelectric conversion efficiency. As an important part of DSSC, the slight difference in structure of photosensitive dye will lead to significant difference in device performance. However, the experimental design and synthesis of efficient dye molecules are still facing great challenges. In recent years, quantum chemistry method has become a reliable research method to reveal the relationship between molecular structure and properties of dyes. This paper mainly includes two parts: in order to reasonably explain the relationship between molecular structure and properties of dithiophene dyes, density functional theory (DFT) and time-dependent density functional theory (TDDFT) are used to discuss the UV-vis absorption spectrum, light capture efficiency and electron injection driving force. A series of theoretical parameters affecting dye performance, including vertical dipole moment and electron transfer number, show that the lower dye regeneration efficiency of dye molecules can lead to smaller short circuit current when there is little difference between light capture efficiency and electron injection efficiency. At the same time, when the number of electrons transferred from dye molecule to semiconductor induced by light and the degree of electron recombination are not much different, the larger dipole moment of dye molecule in vertical direction can lead to higher open circuit voltage. Part two: in order to reveal the relationship between the structure and properties of D 鈮

本文編號：2507264