Optimization and characterization of a single junctionsolar cell based on thin-film a-Si:H/a-SiGe:H heterostructure

In amorphous thin film p–i–n solar cell technology, a thick i-layer (absorber) can absorb more light to generate carriers;however, this also degrades the drift electric field for carrier transport. On the other hand, thin absorbers cannot absorbenough light but can achieve effective collection of generated carriers. Film thickness is one of the most importantparameters that can limit the performance of amorphous silicon thin film solar cells. Introducing Ge atoms to the Silattice in Si-based solar cells is an effective approach in improving their characteristics. Especially, current density ofthe cell can be enhanced without deteriorating its open circuit voltage, due to the modulation of material band-gap andthe formation of a hetero-structure. The electrical parameters of an a-SiGe:H solar cell, such as the open-circuit voltage(VOC), short circuit current density (ISC), fill factor (FF), and the efficiency are investigated in this work, based on theoptimization of the Ge content in the film, thickness of i-layer and doping concentration of p-layer. The concentrationof Ge was changed between 0% and 30%. The band-gap of SiGe plays a critical role in the solar cell design. This workpresent a novel design procedure and investigate optimization thickness and doping concentration of i-layer in a( playera-Si:H/i-layer a-SiGe:H/n-layer a-Si:H) single junction thin film solar cell for use in multijunction thin film solarcells and maximum efficiency of 18.4% is obtained.

Keywords:

Amorphous silicon , Amorphous solar cell , Amorphous silicon solar cell simulation , a-Si/a-SiGe , Silicon-Germanium