Study On The Transparent Electorde And Transporting Layer Mateirals Of Polymer Solar Cells

Polymer solar cells have shown great promising potential in the field of photovoltaic cells and becomeone of hot issues of organic photovoltaic devices because they are simple manufacture, low cost, flexibleand easily to produce in large quantities et al. There is a briefintroduction of the development of polymersolar cells history, current situation and their relevant theory in this paper. Recent researches are mainlyconcentrating on new materials selection and structure optimization. With the purpose of optimizing thestructure of the device, we studied a transparent conductive film, as a candidate of the transparent electrodematerials of the organic solar cells. We also studied the effects on the performances of the polymer solarcells based on P3HT:PCBM showed by the transporting layers.As a usual transparent electrode of the polymer solar cells, ITO is much expensive, so researchersdeveloped some new transparent conductive film used as the transparent electrode. We prepared theSnO₂/Cu/SnO₂multilayer by magnetron sputtering at room temperature. Several analytical tools such asHall measurements, four-point probes and ultraviolet-visible-near infrared （UV-Vis-NIR）spectrophotometer were used to explore the causes of the changes in electrical and optical properties. In theexperiment, it is found that when the thickness of the Cu middle layer is6nm, the multilayer has the bestperformance, showed an average transmittance of82.0%in the region of400-800nm and a sheet resistanceof20.1/sq., performed a good transmittance in visible light and good conductivity.Vertically aligned ZnO nanowires have the structure that can supply the Donor-Accept materials moreinterface, and more efficient transmission path for the electrons, so were widely applied in the solar cells.We prepared the ZnO seed layer using a Sol-Gel method, and carried out the hydrothermal growth ofvertical ZnO nanorods on it. Several analytical tools such as X-rays diffraction, scanning electronmicroscope and ultraviolet-visible-near infrared （UV-Vis-NIR） spectrophotometer were used to examinethe structure and the characteristics of the sample. It turned out that we prepared the vertically aligned ZnOnanowires which have a good orinentation and dense arrangement using the simple method. ZnO film wasdeposited by magnetron sputtering as the electron-transporting layer to fabricate theITO/ZnO/P3HT:PCBM/Ag device. Measuring its photovoltaic performance, it showed a performance with an open circuit voltage of0.443V, short circuit density of6.34mA/cm2, fill factor of21.9%, and powerconversion efficiency of0.614%.MoO₃films were deposited by magnetron sputtering to replace the PEDOT:PSS, as the hole-transporting layer of the ITO/MoO₃/P3HT:PCBM/Al polymer solar cells, and a PEDOT:PSS device wasalso fabricated to compare the performance. Several analytical tools such as X-rays diffraction andultraviolet-visible-near infrared （UV-Vis-NIR） spectrophotometer were used to examine the characteristicsof the sputtered MoO₃films. The deposition temperature of sputtered MoO₃was ranging from roomtemperature to400°C, and the best performance of the devices was observed at400°C, shown an opencircuit voltage of0.587V, short circuit density of8.42mA/cm2, fill factor of51.1%, and power conversionefficiency of2.53%, better than the PEDOT:PSS compared device whose had a power conversionefficiency of2.53%fabricated at the same condition. We also measured the stability of the photovoltaicperformance showed by the devices. After kept120h in ambient air conditions without any encapsulation,the PEDOT:PSS cell only remained a power conversion efficiency value of0.065%, but the optimizedMoO₃device still had a power conversion efficiency of nearly1%. So the stability of the photovoltaicperformance of the device will enhance using the sputtered MoO₃to replace the PEDOT:PSS as thehole-transporting layer.