10.07.2015   SonSolar

Simulation of SSC physical characteristics

Complicated spatial structure of SSC can lead to achieving higher efficiency, therefore optimization of technological steps and parameters must be based on considered SSC. For optimization of spatial SC must be evaluated impact of spatial structure to physical properties of SSC and technological possibilities for production of SSC with optimized physical characteristics.

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Fig. 8. Segment for photocurrent evaluation.

Theoretical bacground for simulation [6] is provided considering the Spatial Solar Cell (SSC) with the configuration presented in Fig. 7, where: the p-n junction segments 4, 5 with Ohmic contacts are the active part of SC; the segment 2 is the p+ — p junctions; the photocurrent generated by the light carriers is collected at the segments 4,5.

The solar cell efficiency of the sunlight conversion into electrical power depends on the maximum value of the power generated by the SC and the density of the incident light power [6]:

V =

m m

Fig. 8. SSC fragment used for

simulation wherePn is density of the incident light power.

The same media are used in solar cell manufacturing processes, but the media sequence is different. So their evolution graphs and resulting solar cells differs appreciably.

For simulation was used fragment of SSC presented in Fig. 8. I(U) characteristic (Fig.

9) is close to theoretical for (m)Si SC.

Proposed model can be used for evaluation of characteristics of SSC.

Variation of geometrical parameters when other parameters are constant proved that only some of geometrical parameters influence SSC efficiency to large degree.

Constant parameters used in experiments: light absorption coefficient a = 0.1 1/ц, thickness D = 300 ц, a = 10 ц, diffusion length Ln = 100 ц, diffusion coefficient Dn = 25 cm2/s, recombination rate Sn =

1.0- 108 цЩ recombination rate S_Air =

1.0- 107 ^s, photon energy hv = 1.6 eV.

In Fig. 10 are presented example results enabling to predict optimized structure for Spatial Solar Cell.

Summary

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U(V)

Fig. 9.1(U). Optimal parameters:

Fig. 9. Dependencies of SSC efficiency on thickness of segment b for different values of segment c: (1) c = 10p, (2) c =100p.

Self-formation emerged as a method to increase the performance of products by using a simpler manufacturing process — with associated significant reduction of manufacturing costs — in the field of semiconductors (including PV cells manufacturing), fuel cells, molecular electronics, etc. Fundamental research, laboratory work and experiments, have already demonstrated the large technological potential for Self-formation. In this paper we presented self-formation possibilities for simplification and cost reduction in Spatial Solar Cell technology. As it was expected self-formation methods are fully applicable for such technology and can be used for production of highly efficient and lower-cost SSC.

Developed software for simulation of physical characteristics of Spatial Solar Cells depending on geometry and material properties can be used for evaluation of optimal characteristics of SSC and further optimization technological processes. First estimations demonstrate significant reduction of the production costs for SSC produced by Self­formation technology.

We also expect that proposed method for optimization of SSC performance can become a useful tool for technologists predicting and optimizing SSC properties and also in searching and predicting new SC

[1] .