Preparation Of Nanometer Mn-ZnO And Their Application In Polymer Solar Cells

Due to the issues of traditional fossil fuels such as nonrenewable and environmental pollution problem,the utilizationof new and clean energy is becoming more and more important.Solar energy is an inexhaustible and clean energy,so utilization of solar energy has attracted much attention.Compared with the silicon-based and dye-sensitized solar cells,organic solar cells have the advantages such assolution processable,low cost,flexible and environmental protection,becoming one of the most promising photovoltaic devices.The introduction of nanoparticles(NPs)layer,can significantly improve the optical performance of organic photovoltaic device.Due to ZnO NPs have high transmittance,good stability,low cost,high carrier mobility and so on,so they were widely used in organic solar cells.However,as a result of broad-band gap for pure ZnO NPs,the poorly conductive ability leads to small short-circuit current in the device,limiting photoelectric conversion efficiency of the device.In this paper,in order to further improve the performance device and overcome the deficiency of pure ZnO NPs,we synthesized Mn doped ZnO NPs with good conductivity by simple thermosolvent method at low temperature,and fabricateda series of polymer solar cells with Mn-ZnO NPs as a buffer layer or amixde dactive layer.Then hanced performance of the devices was achieved.The detailed contents of this study were listed as follows:(1)Pure ZnO and Mn-ZnO NPs with the size of ~5nm were synthesized by thermosolvent method at a low temperature of 65 oC,the phase sturcture,morphology and light transmittance were chracterized by X-ray diffraction(XRD),transmission electron microscopy(TEM)and UV-VIS spectrophotometer.(2)Based on the homogeneous ZnO/Mn-ZnO NPs solution prepared by being dispersed in organic solvent,polymer solar cells with ZnO/Mn-ZnO NPs films as the buffer layer(the electron transport layer)in conventional and inversion structure were prepared by spin-coating method.The photovoltaic performance of the devices shows,compared to the similar devices with pure ZnO NPs layer,the conventional devices with Mn-doped ZnO NPs can achieve photoelectric conversion efficiency of 1.19%,an increase of 42.2%;The inversion device with Mn-doped ZnO NPs can achieve photoelectric conversion efficiency of 1.53%,an increase of 56.1% compared to the similar devices with pure ZnO NPs layer.The improved mechanism of photovoltaic performance for Mn-doped devices was also analyzed.(3)Polymer solar cells with organic P3 HT mixed with ZnO/Mn-ZnO NPs films as the active layer were prepared by spin-coating method.The photovoltaic performance of the Mn-doped ZnO devices shows a photoelectric conversion efficiency of 1.13% can be achieved,an increase of 63.7% compared tot he similar devices with pure ZnO NPs.The enhanced mechanism of photovoltaic performance for Mn-ZnO NPs as the mixed activelayer was also analyzed.