In my study, I attempted to use the high electrical conductivity of graphite modified TiO2 nanoparticles to study the effect of graphite modification to the performance of dye-sensitized solar cell. Graphite oxide (GO) was successfully prepared by the improved Hummer¡¦s method. Graphenes that from the as-prepared GO reduced with hydrazine hydrate and sodium borohydride were characterized by Fourier transform infrared spectroscopy (FT-IR) and UV-visible spectroscopy. The performance of TiO2 based DSSC revealed a short-circuit photocurrent density of 11.24 mA/cm2, an open-circuit voltage of 0.66 V, and a fill factor of 0.48, yielding an overall conversion efficiency of 4.50%. The TiO2 / r-GO composite based DSSC showed higher efficiency than those standard DSSC, revealed a short-circuit photocurrent density of 18.48 mA/cm2, an open-circuit voltage of 0.68 V, and a fill factor of 0.51, yielding an overall conversion efficiency of 7.83%. On the other hand, we found the DSSC that treated with small amount of alcohol in making the TiO2 paste showed superior performance to that with untreated photoanode, the ratio of energy conversion efficiency being 7.11% to 4.50%.

In this work, we study the technique of Titanium Dioxide(TiO2) work electrode of the dye sensitized solar cells. The research contained four parts. (I)Fabrication of porous TiO2 with sol-gel method. (II)Compare the efficiency between dense layer non-dense layer. (III)Study the characteristics of nanometer photocatalyzer layer with silver atom on porous layer. (IV)Replace the commercial dye with the novel Discotic Liquid Crystal(DLC) material which we synthesized. We compared different TiO2 particle size, and discovered the efficiency of 20nm particle which made Degussa reached 3.31%. After joining dense layer, the efficiency can be up to 3.75%. Finally, we sprayed a silver atom layer, the device efficiency increase to 4.13%. Because of the cost of the commercial dye, we replace the dye with DLC which were synthesized by ourselves. The efficiency is up to 0.46%. We offer a feasible direction in low cost and high-efficiency at present.

Semiconductors absorb photos with energy greater than their band gap energy may induce electron-hole pairs. In semiconductor physics, increasing charge carrier improves the electric conductivity of semiconductor. The following methodology was taken to investigate the electric conductivity and the electron hole pairs affected performance of a dye sensitized solar cell. I applied 3 specific monochromatic light (365nm, 405nm and 437nm, respectively.) mixed with xenon light and normal xenon light separately illuminating on dye sensitized solar cells. At the assumption of the normalized photon to current conversion efficiency of solar cell illuminated by 437nm monochromatic light is 100%, the normalized photon to current conversion efficiency of the solar cell illuminated by 365nm monochromatic light was only 28%, however, that illuminated by 365nm monochromatic light mixed xenon light raised to 58%. The more intense mixed light produced more excited electrons than only 365nm monochromatic light. The holes generated by 365nm monochromatic light is easier to be captured by the electrons in the more intense mixed xenon light irradiation results in higher photon to current conversion efficiency. The output of photocurrent of the dye sensitized solar cell irradiated by 365nm ultraviolet light mixed xenon light was enhanced most significantly by 6.53% compared with that by normal xenon light irradiation.

In my research, I use sucrose to modify TiO2 nanoparticles to study the influence of sucrose modification in the performance of dye-sensitized solar cell. Two types of TiO2 are used in the experiments, one is P-25 (80% anatase, Degussa, Germany) and the other is ST-21 (100% anatase, Ishihara Sangyo, Japan). The results shows that the solar cells with TiO2 photoanode sintered in N2 has better conversion efficiency than that sintered in air. On the other hand, the TiO2 with 0.08 g/mL sucrose modification and sintered in N2 has the best conversion efficiency than the others with different sucrose concentration modifications and the highest conversion efficiency reaches 5.55 %. The performance of P-25 with 0.08 g/mL sucrose made solar cell is 10.9% higher than that without sucrose modification TiO2 photoanode made solar cell and the performance of ST-21 with 0.08 g/mL sucrose made solar cell is 5.4% higher than that without sucrose modification.

Thesis (M.S.)--Rutgers University, 2008. / "Graduate Program in Physics." Includes bibliographical references (p. 83-87).

Dye-sensitized solar cells (DSSC) have drawn much attention due to their higher versatility and lower production cost compared to inorganic photovoltaics. The top performers of DSSC have achieved power conversion efficiency over 10%, which is comparable to amorphous silicon solar cells. In this work, new photosensitizers and nanostructure for improving the photovoltaic performance of DSSC were developed and evaluated. Two series of cyclometalated ruthenium(II) complex photosensitizer were presented and their photosensitizing properties in DSSC were studied. Eight cyclometalated ruthenium(II) terpyridine complexes with three carboxylic acid groups on the terpyridine ligand were synthesized. Series A (M1 to M4) consist of C,N,N’ ligands substituted with phenyl group whereas series B (M5 to M8) consist of C,N,N’ ligands substituted with m-fluorophenyl group. All of the complexes exhibited broad aborption spectra covering the whole visible spectrum. The complexes in series B generally showed better photovoltaic performance than those in series A in the DSSCs. DSSC fabricated from M7 achieved the highest Voc, Jsc and power conversion efficiency among other DSSC, which were 0.56 V, 7.30 mAcm-2 and 2.63 % respectively. Truxene-core donor--acceptor dyes were presented and their photosensitizing properties in DSSC were studied. Eight dyes with either one donor two acceptors system (T2, B2, T2R and B2R) or two donor one acceptor system (T1, B1, T1R and B1R) were synthesized. Dyes with two acceptors have high molar extinction coefficients originated from the charge-transfer transition band, which are almost two times higher than those with only one accceptors. Both the enhanced absorption and better anchoring geometry on TiO2 contribute to the better photovoltaic performance of the two acceptors dyes in the DSSCs. Devices fabricated from B2 and volatile solvent electrolyte exhibited the best photovoltaic performance among the truxene-core dyes. The Voc, Jsc, FF and power conversion efficiency of the device were 0.59 V, 9.69 mAcm-2, 0.63 and 3.62 % respectively. Dyes based on cyanoacrylic acid anchoring groups (T1, T2, B1 and B2) were found to perform better than those based on rhodanine-3-acetic acid dyes (T1R, T2R, B1R and B2R) in both donor--acceptor configurations. ITO nanorod/TiO2 nanoparticle composite films with the three different types of ITO nanorod with different length (150 nm, 600 nm and 1.5 μm) were fabricated on FTO glass substrate. The transmittance and sheet resistance of the ITO nanorod array on the FTO glass substrate were found decreased with increasing the length of the ITO nanorod. When the ITO nanorod/TiO2 nanoparticle composite films were applied as the anode in DSSCs, the device fabricated from 600 nm ITO nanorod with TiO2 ‘double layer‘ film showed enhanced photocurrent generation. The improved photocurrent generation is suggested to be due to an improved charge collection efficiency at the ITO nanorod back electrode. / published_or_final_version / Chemistry / Doctoral / Doctor of Philosophy

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Thesis (M.S.)--West Virginia University, 2008. / Title from document title page. Document formatted into pages; contains v, 37 p. : ill. (some col.). Includes abstract. Includes bibliographical references (p. 33-37).

Thesis (Ph. D.)--Rutgers University, 2010. / "Graduate Program in Materials Science and Engineering." Includes bibliographical references.