| In recent years, with the rapid development of global photovoltaic industry and the increasingly serious environmental problems, organic solar cells have been attracted widespread attention. Compared to silicon solar cells and compound thin film solar cells, organic solar cells have great potentialities to replace inorganic solar cells with the advantages of low manufacturing cost, simple fabrication, environmental, flexible and roll-to-roll production. At present, the efficiency of organic solar cell devices are far less than that of inorganic solar cells. Therefore, it is worthy to study how to improve the performance of the organic solar cells. The ZnO nanoparticles(NPs) have caused wide attention in organic solar cells with high transmittance, better environmental stability, simple preparation, low cost, low crystallization temperature, high carrier mobility and significant efficiency of solar cells.In this study, the solvothermal method was used to synthesize the ZnO NPs which was 4nm at a very low temperature of 65℃, and the solubility parameters theory is used to disperse ZnO NPs in organic solvents. Finally, we used the ZnO solution prepared to fabricate inverted and conventional organic solar cells. The main research work is as follows:(1) The ZnO NPs which were 4nm, were synthesized by solvothermal method at a very low temperature of 65℃.The phase and morphology of the ZnO NPs are investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM).Then, a mathematical calculation method has been summed up on the basis of the solubility parameter theory, and successfully has been applied to the ZnO NPs dispersion experiment. The accuracy of the mathematical calculation method based on the solubility parameter theory has been proved, and the optimal ratio has been found under the PL spectra, atomic force microscope (AFM) test method. In this way, we provided a simple, efficient, environmental method to prepare the inorganic nanometer organic solution which was served for organic solar cells behind.(2) A novel and convenient ZnO electronic transport layer, applied in the invert organic thin-film solar cells, was prepared on the basis of the theory of solubility parameter method. The method does not need any surfactant material to modify ZnO NPs, but uses the theory of solubility parameter to adjust proportion and variety of polar and nonpolar solvents which is used to disperse ZnO NPs. Atomic force microscope (AFM) measurement showed that the roughness of ZnO thin film is low and the density is high.The thin-film can improve the efficiency of the inverted device through the way of reducing the leakage current and the parallel resistance significantly, which results in promoting the electronic collection. The device with ZnO NPs optimized as the electronic transport layer exhibits the PCE of 2.55%.(3) The conventional organic solar cells device were prepared by the organic solvent blending method. The device which is based on the hybrid active layer system of P3HT:ZnO thin film exhibits the open circuit voltage of 0.61 V, the best fill factor of 0.46, the PCE of 0.6%. The transmission spectra of the P3HT thin film and the P3HT:ZnO thin film showed that there is a shoulder peak at 600 nm with the increase of ZnO in the absorption spectra. In addition,in the process of vacuum evaporation Al electrode, the ZnO which was used as electronic transport layer of conventional device generated the Al-ZnO phase. This kind of structure is beneficial to the electronic collection. |
PDF Full Text Request