Modelling intermediate band solar cell using finite difference method

The Intermediate band solar cell which is obtained through disposing an intermediate band into the base region of semiconductor material and gained three different energy intervals thus providing more energy interval photon absorbing without decreasing output voltage, is mathematically remodeled by using finite difference method. Necessary integral equations are solved using trapezoidal rule. The equations that we obtained using finite difference method are solved using Gauss elimination method. As a result of these calculations, the effects of carrier mobility?s, light concentration, density of states, base region width and intermediate band energy level on the efficiency are obtained. Besides, the effects of these parameters, on the carrier concentration and current density variations along the base region are also investigated. The optimum band gap value of 1.95 eV is used during calculations and it is seen that the results are in agree with literature with neglecting nonlinear effect. The maximum efficiency value is obtained as 63.8% when the density of states is equal or over to 1019 cm-3 and the mobility is higher than 2000 cm2/Vs. An important amount of decrement in the efficiency is seen when the density of states is lower than 1017 cm-3 the mobility is lower than 200 cm2/Vs. It is obtained that efficiency shows a logarithmic increment with the light concentration. It is observed that the optimum base width should be 5 µm to ensure optimum absorption when the mobility is higher than 200 cm2/Vs. It is shown that the same optimum intermediate band level of 0.71 eV is found using finite difference method. Finally, the effects of emitters are added to the model and the effect of emitter thickness on the efficiency is investigated.