Theoretical Study of Dyes Anchoring onto the TiO2 Surface in DSCs and Their Relevant Properties
| Autor: | Shih-Hung Liu, 劉士弘 |
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| Rok vydání: | 2013 |
| Druh dokumentu: | 學位論文 ; thesis |
| Popis: | 101 Chapter I: Theoretical Study of N749 Dyes Anchoring on the (TiO2)28 Surface in DSCs and Their Electronic Absorption Properties In chapter I, we have performed calculations on the panchromatic N749 dyes adsorbed on the (TiO2)28 surface. N749 is a prototypical form of Ru(II) complexes for dye sensitized solar cells (DSCs), which possesses a terpyridine tridentate ligand bearing four different protonation states (0, 1, 2, or 3 carboxylic protons). Depending on the type of proton bonding interaction (protonated and deprotonated), seven N749/(TiO2)28 surface models (N749-0H/(TiO2)28, N749-1H-P/(TiO2)28, N749-1H-DP/(TiO2)28, N749-2H-P/(TiO2)28, N749-2H-DP/(TiO2)28, N749-3H-P/(TiO2)28, and N749-3H-DP/(TiO2)28) have been applied in this study for the geometry optimization, frontier molecular orbital level diagrams, and calculated absorption spectra. The moderate surface area of (TiO2)28 cluster is suitable for N749 dyes adsorbing behaviors so that all calculations can be performed using the Gaussian 09 program package. We have carefully examined these seven N749/(TiO2)28 assemblies that could influence the DSCs device performance. The calculated absorption spectra of these seven various N749/(TiO2)28 models are in good agreement with the experimental results by Hagfeldt et al. [J. Phys. Chem. B, 2002, 106, 12693–12704] with onset ranging from visible to near-IR region. The combination of the adsorption energy onto TiO2 and calculated absorption spectra (c.f. the experimental results) concludes that the deprotonated dyes constitute the most favorable and dominant structure in the DSCs devices. The frontier molecular orbital graphs indicate that the electron charge distribution of all HOMOs are located at the N749 dyes while LUMOs are localized at the (TiO2)28 surface or delocalized at the interfacial regions of N749/(TiO2)28. The corresponding transitions are thus more like a type of optical electron transfer, injecting the electron to the interfacial TiO2. Chapter II: Tridentate Terpyridine Os(II)– and Ru(II)–Based Dyes Anchoring on the (TiO2)38 Surface in DSCs – A Theoretical Study In Chapter II, in the past decade, Os(II)–based panchromatic dye sensitized solar cells (DSCs) are an alternatively accessible choice to replacing the traditional heavy metal Ru(II)–based dyes. In 2012, we reported two synthesized Os(II)–based dyes with photo-current conversion efficiency reaching 8.85% in our experimental research. In this theoretical study, we performed the simulation regarding two Os(II)– (TF-51-Os and TF-52-Os) and two Ru(II)–based (TF-51-Ru and TF-52-Ru) dyes anchoring onto the anatase (101) (TiO2)38 surface. In total, we simulated four dye/(TiO2)38 surface models. Based on the same structures (TF-51-Os vs. TF-51-Ru and TF-52-Os vs. TF-52-Ru), we could make a comparative study relating the Os(II)– and Ru(II)–based dyes in DSCs. By the way, we also quantitatively estimated the electronic coupling between the dye and (TiO2)38 interfacial interaction using the Generalized Mulliken–Hush (GMH) theory with configuration–interaction singles (CIS) method. This article is the first report theoretically studying about the Os(II)–based dye in DSCs, and we believe that it could open a new doorway in the heavy metal based dye/TiO2 research field. |
| Databáze: | Networked Digital Library of Theses & Dissertations |
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