Electron transportation and optical properties of microstructure TiO2 films: applied in dye-sensitized solar cells

• Published in: Frontiers of optoelectronics in China Vol. 4; no. 1; pp. 72 - 79
• Main Authors: Xu, Shuangying, Hu, Linhua, Sheng, Jiang, Kou, Dongxing, Tian, Huajun, Dai, Songyuan
• Format: Journal Article
• Language: English
• Published: Heidelberg SP Higher Education Press 01.03.2011
• Subjects: Biomedical Engineering and Bioengineering; Electrical Engineering; Engineering; Physics; Research Article; micro-structure; electron transport; optical property; dye-sensitized solar cell (DSSC); porosity
• ISSN: 1674-4128; 1674-4594
• DOI: 10.1007/s12200-011-0202-5

Micro-structure of TiO 2 films in dye-sensitized solar cells (DSSCs) can affect light absorption and electron transportation that impact on the characteristics of currentvoltage ( J-V ). In this paper, films with different surface area, pore size and porosity were obtained by adding different ratio of ethyl cellulose (Ec-S) to pastes, and a photo-electric conversion efficiency ( η ) of 7.55% with a short-circuit current density ( J sc ) of 16.81 mA·cm −2 was obtained when the ratio of Ec-S was 10:5. BET results showed that film with this optimum ratio had the most suitable pore size and surface area for good properties of photovoltaic, which had a low reflectivity and high transmission rate, and the efficiency of light utilization was improved. Moreover, measurements by intensity-modulated photocurrent spectroscopy (IMPS) and intensity-modulated photovoltage spectroscopy (IMVS) implied that the electron transport time ( τ d ) increased as the content of Ec-S increased, which was related to the larger surface area. Results of steady-state cyclic voltammetry indicated that diffusion-limited current density ( J lim ) of I 3 − in TiO 2 film increased with its porosity, which revealed that the transportation of redox mediators in the electrolyte was speeded up.