Amorphous (Protocrystalline) and Microcrystalline Thin Film Silicon Solar Cells

This chapter discusses amorphous and microcrystalline thin film silicon solar cells. Thin film silicon, like no other thin film material, has been shown to be very useful in tandem and triple-junction solar cells. Such multijunction cells have true potential for high conversion efficiency because of their spectrum splitting capability. Amorphous silicon has a band gap of 1.7–1.8eV, and thus, microcrystalline silicon, with a band gap of 1.1eV, makes an ideal match to amorphous silicon in tandem cells. The research challenges are to enhance the network ordering of amorphous semiconductors, mainly for improving the stability and to increase the deposition rate—in particular, for microcrystalline silicon; to develop thin doped layers, compatible with the new and fast deposition techniques; to design light-trapping configurations, by utilizing textured surfaces and dielectric mirrors. This chapter concludes that, in production, the trend is toward implementation of these multijunction structures in large area modules. Modules are currently produced batch wise, in-line on glass, or roll-to-roll on stainless steel and other foils, such as polymer plastics.