Study On Properties Of Organic Solar Cells Fabricated By Novel Structure

The development of the world economy has been restricted by energy problem all the time, solar energy as environmental protection energy has become a hotspot among the scientists. Solar cells can make solar power into electrical energy, which can effectively resolve the energy crisis. Organic solar cells have been receiving increasing attention due to their amount of advantages, such as simple manufacture process, low cost and large area fabrication.In this paper, the emphasis is focused on the study of small molecule organic solar cells based on CuPc/C60. We hope to make further improvement on the performance of the organic solar cells and carry through the research in some aspects mainly:Firstly, occording to the optical interference and the principle of diffusion, we simulate the light field distributions of organic solar cells based on CuPc/C60. Secondly, we analyse the change of the activation layer thickness that influence the number of excition. Finally, the optimum structure of the device shows as ITO (150nm)/CuPc(20nm)/C60(60nm)/Al(100nm). This result has been helpful to difine the structure of the devices in experiments. Since there are many hypothesises and predigestions in the analysis process, the different result between the experiments and theory should be accepted.On the basis of that optimum structure, an ultra-thin NaCl layer was incerted between the C60 film and the Al cathode by evaporation technique, the output characteristic of the solar cells are improved a lot. The ultra-thin NaCl layer doesn't have any noticeable effect on the light intensity distribution inside the cells, however, the Volt-Ampere characteristics of the cells have been changed significantly. When the thickness of NaCl layer was 1.5nm, compared with none NaCl layer, Short-circuit current densities of the cells were raised by 2.3 times and the open circuit voltage was raised by 7mV, besides, the energy conversion efficiency was also raised by 2 times. And then, we make use of tunneling effect to build up the model, meanwhile, we make a brief analysis of the mechanism of the buffer layer. Finally, we obtained the best optimum thickness of NaCl layer that was 1.5nm via a lot of experiments. If the buffer layer is too thin or too thick, it will induce the attenuation of the device performance.We establish the mathematical model of equivalent circuit and focus on discussing the influence of the non-ideal factor on the performance of solar cells in the end. And then, we simulate and analyse the influence of series resistance and shunt resistance on the open circuit voltage, short-circuit current density and the fill factor. At last, we can make several conclusions that reducing series resistance and increasing shunt resistance can enhance the short-circuit current and fill factor.