Optimization of the PEDOT:PSS/SiNW Hybrid Solar Cells and All-Back-Contact GaAs Solar Cells with Two Dimensional Simulation

The poly(3,4-ethylenedioxythiophene): poly(styrenesulfonate) (PEDOT:PSS)/silicon nanowire (SiNW) hybrid solar cell and the all-back-contact gallium arsenide (GaAs) solar cell are studied in this thesis. We used different simulation methods based on the characteristic of each solar cell to obtain the optical and electrical properties of each solar cell. After analyzing the electrical properties of the PEDOT:PSS/SiNW hybrid solar cell and the all-back-contact GaAs solar cell, further optimization is proposed, respectively. For the PEDOT:PSS/SiNW hybrid solar cell, a numerical model that capable of simulating the organic/inorganic hybrid solar cells was developed. Furthermore, a Gaussian distribution models of tail/interfacial states and trap states are addressed to present this characteristic when simulating the organic/inorganic hybrid solar cells. The 2D-FDTD model was used to model the optical field. After the simulation parameters are verified by fitting the current density-voltage (J-V) curve to the experimental results, the PEDOT:PSS/SiNW hybrid solar cell is optimized. The optimal structure is proposed with a p-type doping Si layer in the SiNW region adjoining to the PEDOT:PSS and an n-type doping Si layer at the rear Si layer near the bottom contact. The highest efficiency of 16.12% could be obtained after the optimization. For the GaAs solar cell, an all-back-contact is employed to the GaAs solar cell. By investigating the electrical properties of the all-back-contact GaAs solar cell, we are able to find the optimum structural design. A thicker base layer can reach a higher generation current, but it can also lead to a higher recombination. Therefore, the base layer thickness is suggested to be 1.5 um. For a wider n-contact width, a higher Jsc can be obtained, but the recombination at the p-n junction region becomes larger, which deteriorates the FF. Consequently, the n-contact width is recommended to be 600 um. The best efficiency up to 25.12% could be achieved with the suggested structure.