Book Description

Textured back reflector (BR) is an essential component used in substrate type solar cells for light trapping, which enhances the long wavelength absorption. Most commonly used BR consists of a reflecting metal layer(s) of Ag and/or Al and a transparent conducting oxide (TCO) layer such as ZnO. This type of BR, if properly textured, can lead to about 20% increase in the short-circuit current and cell efficiency. A widely used technique for producing the BR is sputtering due to its simplicity and easy operation for large area thin film solar cell applications. The TCO layer needs to be thick enough (>500 nm) to reach a textured structure and to prevent the metal in the BR from diffusing into the solar cell layers. Thus, the ZnO deposition becomes the bottleneck in the BR process. Significant efforts have been putting on developing novel techniques that can produce ZnO coatings with better texture and high deposition rate. To address the above issue electrodeposition was employed to coat ZnO film, because it gives high deposition rate at low cost. A systematic study of conventional electrodeposition was performed. Further improvements for the electrodeposition process have done to eliminate some of the problems associated with conventional electrodeposition. In addition highly textured BR produced by electrodeposited ZnO changes the electrical structure of the device. The necessity to consider these factors when fabricating solar cells on highly textured BR was emphasized using PVOPTICS and AMPS modeling. Hydrogen is considered to be the fuel of the future. Subsequently there are many attempts of generating H2 by environmentally friendly means. One such proposed system is photo-electrochemical cell (PEC) consist of transparent conducting corrosion resistive (TCCR) layer, a-Si:H solar cell and catalytic layer. The research work done to identify the potential TCCR layers and fabrication of porous nickel catalyst layer will be discussed.