Ultrasonic Spray Deposition In Preparation Of Polymer Solar Cells And Phase Structure Optimization

The rapid growth of population and the development of world economy have led to the continuous growth of human demand for energy.The huge consumption of traditional fossil energy has led to a series of environmental problems.It is urgent for human beings to find new renewable energy to promote the development of cities.In contrast,the solar energy in many renewable energy because of its characteristics such as rich resources,and is not subject to regional restriction,polymer solar cells in the development of recent decades also because of its light weight,high flexibility,low cost and large light absorption coefficient,and the economic feasibility of the wearable electronic devices such as application fields has received the attention of the researchers.In this paper,polymer solar cells based on PBDB-T-2Cl:IT4F system were prepared by solvent engineering and segmented spraying process.The morphology and phase structure of the active layer of PBDB-T-2Cl:IT4F polymer solar cells were optimized,which broke through the traditional preparation method and significantly improved the device performance.The main research work and results are as follows:(1)Solvent engineering was used to optimize the active layer morphology and phase structure of PBDB-T-2Cl:IT4F polymer solar cells,and the mechanism of low polarity triple symmetric non-halogen benzene derivatives and benzene pair morphology and device performance was systematically discussed by means of multi-solvent method.The morphology,composition and phase structure of PBDB-T-2Cl:IT4F blend film were tested and characterized by J-V,AFM,XPS and GIWAXS.The results showed that the triple symmetric non-halogen benzene could promote the face-on orientation of PBDB-T-2Cl:IT4F blend film,and the morphology of the active layer could be improved by reducing the coffee ring or other defects.During the annealing process,the donor material PBDB-T-2Cl can migrate to the surface of the blend film,which is conducive to the formation of vertical phase separation.Adding 20%benzene or triple symmetric non-halogen benzene derivatives in the preparation of the active layer solution can significantly improve the performance of the devices.The devices prepared by the mixture of 20%TMB and80%CB have the best morphology and phase structure,and the photoelectric conversion efficiency is improved by nearly 60%compared with the devices prepared by only 100%CB as the solvent.(2)The solvent driving force was formed with the assistance of solvent engineering based on 1,3,5-trimethylbenzene,and the continuous interface of the active layer was formed by piecewise spray.Results show that the piecewise spray has the advantage that the control component distribution,blend film formed in the active layer bi-continuous interpenetrating network structure,namely the perpendicular phase separation structure,electrons and holes can be efficiently to electrodes on both sides of the transmission,reducing the double molecular compound,at the same time enhance the external quantum efficiency,to improve the device performance significantly.The donor/recipient ratio was 1:2 on the first spray and 2:1 on the second spray,and the coating thickness was 90nm for each spray.The performance of photovoltaic devices based on PBDB-T-2Cl:IT4F system has been significantly improved.The photoelectric conversion efficiency reaches 12.29%,and the short-circuit current is up to 21.55 m A/cm~2.More importantly,a large area of PBDB-T-2Cl:IT4F photovoltaic device was successfully prepared by using the section spraying process under the optimized conditions,and the photoelectric conversion efficiency reached 6.68%,which indicates that this section spraying technology can be used in the commercial manufacturing of large area polymer solar cells.