Polymer Solar Cells Based On Cathode Buffer Layers And Cathode Buffer Layers Physical Modification

Recently,the consumption of fossil energy has become more and more serious,and the energy issue has become a key strategic issue of concern to the world.As a renewable energy source,solar energy is an ideal alternative energy source.Photovoltaic technology that converts solar energy into electrical energy has become a research hotspot in various countries around the world.Solar cells that are currently commercialized are silicon based on inorganic semiconductors,but their applications are severely limited due to their high quality requirements for source materials,complex preparation and molding,and high production costs.Compared with inorganic semiconductor photocells,organic solar cells have attracted worldwide attention due to their advantages such as simple fabrication process,light weight,and the ability to fabricate flexible devices.However,at present,the energy conversion efficiency of organic solar cells is lower than that of inorganic solar cells,and there is still a long way to go from large-scale commercialization,and it needs further development.The details of experiment are shown as follow:Firstly,we used the alcohol-soluble polymer PFN as the cathode interface layer.Compared with no interface layer,the open circuit voltage(Voc),short circuit current(Jsc),and fill factor(FF)of the device can be greatly improved.The energy conversion efficiency of the organic solar cell device is improved.Relevant studies have shown that the existence of interface dipole moment is the main reason for the increase of the open circuit voltage of the device.At the same time,the space charge analysis method is used to measure the carrier’s mobility of the device,which proves that it can improve the carrier’s mobility and thus improve the short-circuit current and fill factor of the device.Compared with the alcohol-soluble polymer PFN as the cathode interface layer,we also used several other alcohol-soluble polymers as the cathode interface buffer layer.For example: PBSON-FEO、PBSON-P and so on.Under the same device structure,the device performance is similar or even better PFN acts as the cathod interface layer,but we have found that regardless of whether the PFN is used as the cathode interface layer or other alcohol-soluble polymers,the resulting device is sensitive to the interface layer thickness.The main reason is that once the thickness of the interface layer is increased,the overall performance of the device is degraded because of its low electrical conductivity.This main problem greatly limits the application of such interface layer,and therefore needs to be solved.In order to further study the effect of interface layer conductivity on device performance,in the fourth chapter of this paper,The electron transport material 4,7-diphenyl-1,10-phenanthroline(Bathophenanthroline,Bphen)as a guest,PFN as the main body,studied by physical doping modification methods to improve the PFN interface layer Charge transfer performance.It was found that due to the higher HOMO energy level,Bphen doping can maintain the good hole-blocking performance of the PFN interface layer,at the same time,it can improve the electrical conductivity and charge transport ability of the interface layer,and improve the electron mobility of the device,improving Device performance.This study shows that modification by physical doping is an effective method to improve the charge transport characteristics of the PFN interface layer,and provides new ideas for further expanding the application of PFN interface layer.