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Tham khảo tài liệu 'solar cells dye sensitized devices part 15', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 412 Solar Cells - Dye-Sensitized Devices materials in DSSCs Argazzi et al 2004 . Electrochemical impregnation from salts and physical deposition such as sputtering are commonly employed to deposit platinum thin films. Chemical reduction of readily available platinum salts such as H2PtCl6 or Pt NH3 4Cl2 by NaBH4 is a common method used to obtain platinum electrodes. Platinum has been deposited over or into the polymer using the impregnation-reduction method Yu et al 2005 . It is known that the final physical properties of Pt thin films depend on deposition method. Figure 11 shows SEM images of platinum thin films deposited by sputtering and electrochemical method as function of substrate type. Figure 11 a corresponds to TCO substrate without platinum thin film and Figure 11 b shows a platinum thin film on TCO substrates deposited by electrochemical method. It is clear that TCO substrate grain size is smaller than platinum thin film grain size this figure shows different size grain and Pt particles distribute randomly through out the substrate surface this image shows some cracks in some places of the substrate. Furthermore figure 11 c shows platinum thin films deposited on TCO by sputtering method it shows that platinum thin films have better uniformity than platinum thin film deposited by electrochemical method and the size grain is greater than size grain of thin film deposited by electrochemical method. In fig. 11 c the Pt particles are distributed randomly through out the substrate without any crack this is different to the electrochemical method and indicates that the surface is uniformly coated. This thin film is less rough and corrects imperfections of substrate. Finally platinum thin film grown on glass SLG shows both smaller size grain particles and lower uniformity than platinum thin film deposited on TCO Quinones Vallejo 2011 . Fig. 11. SEM images 20000x from a TCO substrate b Pt TCO by electrochemical method c Pt TCO by sputtering d Pt SLG by sputtering
