Nanocrystalline silicon-based multilayers and solar cells

Abstract

Nanocrsytalline Silicon (nc-Si) is a promising material to develop the next generation of solar cells since it can efficiently absorb the incident solar light in a wide spectral range via the size modulation. The idea of all Si-based tandem type solar cells containing the sub-cells with various bandgaps motivates the extensive studies on the synthesis, physical properties, as well as the device applications of nc-Si material. Currently, the fabrication of size-controllable nc-Si is one of the challenging issues and the utilization of nc-Si in actual photovoltaic device is still at the stage of exploration. In this chapter, we describe the preparation of size-controllable nc-Si dots in multilayer by using thermally annealing or laser crystallization technique to crystallize amorphous Si/SiO2 or amorphous Si/SiC stacked structures. It is shown that the dot size can be well confined with the initial amorphous Si layer thickness and the size-dependent properties are observed. The chapter focuses on the utilization of prepared nc-Si-based multilayers in prototype hetero-junction solar cells. The photovoltaic properties with different dot size, surrounding insulator materials, as well as the novel grade-sized structures are present. Furthermore, the efforts to improve the device performance by combining light trapping structures with nc-Si-based multilayers are introduced.