Preparation Of TiO₂ Composite Nanofibers And Its Application In DSSC

As a photoelectric device for converting solar energy,dye-sensitized solar cell(DSSCs)has become the leader of the recent solar cell with the advantages of simple technology,low cost,green environmental protection.However,the efficiency of the DSSC is still to be improved,and the photoelectric conversion efficiency of the cells can be improved from two aspects.One is to increase dye absorption to enhance solar absorbance,the two is to enhance the efficiency of photoelectron transmission.In this paper,one-dimensional nanofibers are prepared by electrospinning to improve the effectiveness of the electron transport.At the same time,electrospun nanofibers have specific surface area,moreover,doped the TiO2 nanofibers with graphene,nitrogen and black phosphorus can enhance the optical absorption capacity of the optical anode and improve the transmission efficiency of photoelectron generation to enhance efficiency.The following is the specific research content of this paper.First,the graphene-TiO2 nanofibers are prepared by electrostatic spinning.The composite fibers,such as the proportion of graphene,the voltage,the speed of the inlet liquid and the heat treatment temperature of the fiber are studied.The SEM,TEM,XPS,Raman and the UV-Vis analysis found,while the pressure is 17 kV,speed is 0.6 ml/h,graphene content is 0.6 wt%,and the heat treatment temperature is 550 ?,the graphene-TiO2 nanofibers have good appearance which benefits electronic transmission.Secondly,we further optimizied the graphene-TiO2 fibers by nitrogen and black phosphorus.The nitrogen was doping into graphene-TiO2 fibers by hydrothermal.It displayed that the nitrogen-graphene-TiO2 fibers successfully obtained by hydrothermal through the XPS test.The TEM test showed that the nitrogen crystal grew evenly on the surface of the composite fiber.UV-Vis test indicated that the visible light absorption strengthen.Next,we prepared nano phosphorus by liquid phase stripping.The diameter of black phosphorus studyed by TEM and AFM was in the range of 200-300 nm and the thickness was 10-30 nm.By Raman analysis,it showed that the nano black phosphorus was the same as the characteristic peak of fewer layer black phosphorus,indicating that the prepared black phosphorus was two dimensional nanomaterial,and we combined the nano black phosphorus with the electrospun composite fiber by self-assembly method.In general,Co-doping graphene-TiO2 nanofibers can improve the properties of graphene-TiO2 nanofibers and enhance their absorptive capacity to sunlight.Finally,we applied the graphene-TiO2 fiber obtained by electrostatic spinning,as well as the Co-doping fiber of nitrogen and black phosphorus to the cells,and the performance of the cells were tested by J-V curve and IPCE.The test results showed that the cell efficiency of 0.6 wt%graphene-TiO2 nanofibers was the highest.After Co-doping,the efficiency of the clells increased 26%,while the efficiency of the black phosphorus doped cells maximum increase 32%.The IPCE test of all cells found that the IPCE curve of nitrogen-graphene-TiO2 is the highest,and the black phosphorus graphene-TiO2 is the same,which is in accordance with all the statistical results of the conversion efficiency of all cells prepared in this paper,that is,the efficiency of nitrogen graphene-TiO2 is the highest.This shows that the nitrogen element is better than black phosphorus to promote the performance of DSSCs when Co-doped electrospun graphene-TiO2 nanofibers.In general,through the study of the morphology of the electrospun graphene-TiO2 fiber,the best process parameters are summarized,and the graphene-TiO2 composite fiber under this condition is the framework.By means of liquid stripping method and low power ultrasonic assistance,the nano phosphor with diameter of 200-300 nm and thickness of 10-30 nm was obtained.The electrospun graphene-TiO2 nanofibers were doped with nitrogen and nano black phosphorus respectively.It was found that the increase rate of photoelectric conversion efficiency was greater after nitrogen doping,while the cell efficiency increased less when black phosphorus doped graphene-TiO2.The study of Co-doping TiO2 fiber with different graphene content and applying it to the photo anode is not at present,but the research in this paper will provide a useful reference for the study of Co-doping graphene-TiO2 nanofibers to improve the efficiency of dye-sensitized solar cells.