Research On Planar-Bulk Integrated Heterojunction Polymer Solar Cells

Polymer solar cells have the advantages of low cost,light weight,simple preparation process and large-area preparation,and are receiving more and more attention as one of the solutions to human energy problems.At present,the power conversion efficiency of single-juction polymer solar cells has exceeded 14%.However,in order to commercialize polymer solar cells,the efficiency and stability of the devices need to be further improved.There are many factors affecting the performance of polymer solar cells.The morphology of the active layer directly affects the separation and transmission of charges,which in turn affects the overall performance of the device.Therefore,it is necessary and meaningful to study how to obtain a more ideal active layer morphology.In this paper,a planar-bulk-integrated heterojunction was prepared by solution processing,and its corresponding polymer solar eells were studied,mainly as follows:1.We prepared the planar-bulk integrated heterojunction polymer solar cells based on the polymer donor PTB7-Th and the non-fullerene acceptor ITIC-M by using suitable solvents(chlorobenzene and phenetole)with solution sequential process and solvent-assisted annealing.By comparing and analyzing the morphology,surface potential and water contact angle of the active layer prepared by the traditional method,the solution sequential process,the the solution sequential process and solvent-assisted annealing,it is proved that the new method can be used to prepare the active layer structure which is more ideal than the traditional method.The power conversion efficiency(PCE)of the device prepared by the solution sequential process and the conventional method is similar,which is 5.22%and 5.25%,respectively.The PCE of device prepared using solution sequential process and solvent-assisted annealing is 6.32%.2.Using dichloromethane and a small amount of o-dichlorobenzene as the mixed solvent of ITIC-M,the problem of using phenetole as solvent and not infiltrating the donor PBDB-T film in the previous chapter was solved.Then,the planar-bulk integrated heterojunction polymer solar cells based on donor PBDB-T and acceptor ITIC-M were fabricated by solution sequential process.The power conversion efficiency of the device is 10.37%,which is higher than the efficiency of the device prepared by the conventional method(9.20%).The results of this experiment are consistent with the conclusions of the previous chapter.This indicates that the planar-bulk integrated heterojunction prepared by solution processing is more conducive to the efficient transport of carriers and can reduce the charge recombination probability,which leads to a signifieant increase in the short eircuit current density and fill factor of the device.