Characterization and simulation study of organic solar cells based on donor–acceptor (D–π–A) molecular materials

In this study, the analysis of microelectronic and photonic structure in a one dimension program [AMPS-1D] has been successfully used to study organic solar cells. The program was used to optimize the performance of organic solar cells based on (carbazole-methylthiophene), benzothiadiazole and thiophene [(Cbz-Mth)-B-T]2 as electron donors, and [6,6]-phenyl-C₆₁-butyric acid methyl ester (PCBM) as an electron acceptor. The optoelectronic properties of these dyes were investigated by using the Density Functional Theory DFT/B3LYP/6-31G(d,p) method. We studied the influence of the variation of the thickness of the active layer, the temperature, and the density of the effective states of the electrons and the holes in the conduction and valence bands respectively on the performance of the solar cells based on [(Cbz-Mth)-BT]2–PCBM as a photoactive material, sandwiched between a transparent indium tin oxide (ITO) and an aluminum (Al) electrode. The addition of other thiophene units in the copolymer or the deposition of a layer of PEDOT between the anode (ITO) and the active layer, improves the performances of the cell, especially resulting in a remarkable increase in the value of the power conversion efficiency (PCE).

The solar cell ITO/PEDOT/[(Cbz-Mth)-B-DT]2-A:PCBM/Al under study and the results obtained, including a power conversion efficiency of 11%. The impact of several parameters on the performance has been studied to obtain the optimal device architecture.