Improved analytical current voltage characteristics of a solar cell

Application of the Green’s function method to the calculation of the current voltage characteristics of a pn-junction solar cell makes possible to extract more reliable and exact information about the behavior of the cell. With this method not only the minority carrier diffusion currents but also the drift currents in quasi neutral regions of the solar cell can be taken into consideration. Furthermore, this approach is not limited to an exponentially decaying minority carrier generation function but is valid for any type of optical generation. In addition, the injection boundary condition is exploited with the result that not only the pn-diode current but also the current resulting from the optical generation depends on the voltage of the solar cell. Applying the method also gives the so called position dependent collection efficiency function which is defined as the probability that an electron-hole pair created at a certain point inside the solar cell will contribute to the current leaving the cell.