Numerical analysis of the effects of distributed series resistance and lateral conduction in solar cells

Large-area solar cells are more susceptible to imperfect surfaces, such as edges or cracks. Numerical two-dimensional methods are developed and applied to study the effects of the imperfect surface in solar cells. The two-dimensional effects investigated in this work reveal the lateral conduction of solar cells, which causes inconsistent potentials and a deviation of photocurrent. The mask effects from distributed series resistance on luminescence techniques, such as photoluminescence and electroluminescence, are also explored. Lateral conduction hides the information of the real distribution of defects, and numerical methods are applied to eliminate the effect. In multijunction solar cells, lateral conduction in the interlayer leads to the complementarity between the luminescence of top and bottom cells. Furthermore, the distributed series resistance also causes a knee in the I–V curves, resulting in a decrease in the efficiency of the cell. The research in this work demonstrates that different categories of defects show different influences on solar cells, and the effect is more obvious on the open-circuit voltage rather than the short-circuit current. The study of distributed series resistance and lateral conduction in this work not only gives an explanation of experimental data but also provides instructions for the developments of large-area solar cells.