Modelling of Thin‐film Crystalline Silicon Parallel Multi‐junction Solar Cells

Abstract

The parallel multi‐junction solar cell design has recently been proposed to reduce the costs of photovoltaics, while maintaining or improving device performance. This design uses alternating layers of n‐ and p‐type semiconductor to ensure that every point in the device is much less than one diffusion length from a collecting junction, producing relatively high currents. Device voltages can be maintained through heavier doping than would normally be used. This approach is particularly suited to very low‐quality material where the diffusion lengths are much shorter than the device thickess required for significant photogeneration. In particular, this design strategy is seen as a way to realize the potential of thin‐film polycrystalline silicon solar cells for large‐scale, cost‐effective energy generation. A brief description of the parallel multi‐junction solar cell is presented, along with some analysis where parallel multi‐junction solar cells differ from conventional cells. Results from an analytical one‐dimensional model and two‐dimensional numerical simulations are presented, highlighting some of the significant advantages of parallel multi‐junction solar cells.

Ion beam mixing of silicon-germanium thin films

“…5,6 Current state of the art small-scale cells deliver conversion efficiencies of more than 16%, while larger size modules yield efficiencies around 10 pct. 7,8 Recent work performed by various groups yielded improved efficiencies surpassing 19 pct.…”

“…7,[15][16][17][18][19] In particular, for solar cells, the publications in the area of Si 1-x Ge x alloys have been numerous and a relatively few favorable conclusions for the use of Si 1-x Ge x alloys have been established. 5,6,[15][16][17][18]20 In this work, the authors envision a Si matrix of solar cells adjacent to SiGe cells. Typical Si cells will capture the light in the visible and short infrared (IR) region, while the SiGe cells will enhance the absorption process to the longer IR region.…”