tailieunhanh - Solar Cells Dye Sensitized Devices Part 3

Tham khảo tài liệu 'solar cells dye sensitized devices part 3', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 52 Solar Cells - Dye-Sensitized Devices oxide T1O2. ZnO presents comparable band gap value and conduction band position as well as higher electron mobility than TiO2 Quintana et al 2007 Keis et al 2002 . It can be synthesized in a wide variety of nanoforms Wang et al 2004 applying strainght forward and scalable synthesized methodologies Fan et al 2006 Greene et al 2003 . particularly the application of vertically-alligned ZnO NANOSTRUCTURES it is thought to improve contact between the donor and acceptor material in organic solar cells OSCs or improve electron injection in dye sensitized solar cells DSCs Gonzalez et al 2009 To date DSC based on ZnO have achieved promising power conversion efficiency values of 6 . Keis et al 2002 Yoshida et al 2009 . Yet ZnO is not an easy material. It is a semiconductor oxide the properties of which are greatly influenced by external conditions like synthesis methods Huang et al 2001 Wu et al 2002 Elias et al 2008 Yoshida et al 2009 temperature Huang et al 2007 Guo et al 2005 . Testing atmosphere air vacuum Cantu et al 2006 2007 Ahn et al 2007 or illumination Kenanakis et al 2008 Feng et al 2004 Norman et al 1978 for example minimal changes in the shape of the ZnO nanoparticules nanorods nanotips etc can produce different properties which in turn affects the interface with any organic semiconductor or dye molecule. Moreover the modification of properties likes hydrophilicity hydrophobicity or the amount of chemisorbed species on the ZnO surface have already been reported to be affected by UV irradiation. In DSC a major drawback is associated with the interaction between dye molecules and ZnO itself. Dye loading on ZnO must be carefully controlled in order to obtain the optimal power conversion efficiency for every system. Chou et al 2007 Fujishima et al 1976 Kakiuchi et al 2006 . An excess in loading time results in the formation of aggregates made by the dissociation of the ZnO and the formation of Zn 2 -dye complexes Keis et al .