Modeling and Characterization of Semiconductor Devices for Energy Efficiency

Photovoltaics is among the most important technologies aimed at producing electrical energy from renewable and sustainable energy sources, and its market demands more and more efficient and cost-effective technologies. Numerical device simulation allows understanding the link between new cell's architecture and physical structure, and the underlying physical mechanisms. Moreover, an advanced modeling may be suitable for identifying and analyzing promising solutions focused on the fulfillment of the photovoltaic market requirements. This thesis aims at improving existing solar-cell simulation approaches and developing new ones. Furthermore, one of the challenges tackled by the presented work is to explain several behaviors revealed by the experimental characterization of different solar cell architectures (or concepts) and to provide useful findings to the industrial and experimental reasearch partners through an advanced numerical modeling. This work provides the following contributions: i) the analysis of a new solar cell design conceived for low-medium concentrator photovoltaic applications, the EWT-DGB solar cell. Three-dimensional numerical simulations, calibrated starting from experimental data, are carried out to investigate the performance under concentrated light and the potentials considering possible realistic improvements with respect to the fabricated devices; ii) the role of top/rear poly-Si/SiOx selective contact applied on front emitter silicon solar cells is investigated by means of simulation studies performed by using physical models calibrated on the basis of experimental data. A rear junction design which desensitizes the Fill Factor (FF) to top electrode resistivity is also proposed. In addition, in the field of the modeling of advanced concepts applied on well-known high efficiency solar cells, the impact of a rear point contact (RPC) scheme in metal wrap through (MWT) solar cells with passivated base, the study of the well-known Light-Induced Degradation (LID) effect and electro-optical simulations of multi-wire (MW) and busbars (BBs) based solar cells aimed at evaluating a MW approach, are presented.