| As the main source of clean energy on the earth,solar energy is not only free from environmental pollution,but also inexhaustible.As a classical way to convert solar light into electricity,solar cells have made great progress in recent years.Among them,organic solar cells(OSCs),as an economically feasible and promising clean energy utilization method,have attracted close attention in the research field.All-polymer solar cells(all-PSCs),as OSCs with strong mechanical stability and thermal stability,have achieved an efficiency of more than 10% with unremitting exploration by researchers.Among them,NDI-based N2200,as the most successful polymer receptor with high electron affinity and high electron activity,achieved a milestone progress in all-PSCs.In the second chapter,IDIC was used as the third component of PBDB-T:N2200-based all-PSCs with positive structure and the effect on device performance was studied.IDIC energy levels match those of PBDB-T and N2200,and it is found that IDIC film has a strong absorption coefficient at 500-800 nm,which will make up for the weak absorption of PBDB-T:N2200 film in the wavelength range of 500-800 nm.It was found that when adding IDIC of appropriate specific proportion to PBDB-T:N2200 blend layer,the active layer would form a more uniform and continuous network interpenetrating structure,thus forming a good phase separation.It can also improve the efficiency of charge collection and exciton dissociation.The energy conversion efficiency(PCE)of the device was increased from 6.08%to 6.98%.IDIC as a third component also improves device stability.The third chapter further studies the interface compatibility of all-PSCs based on PBDB-T: N2200 system.It was found that the interface compatibility in the PBDB-T:N2200blend layer was greatly improved after the addition of a pair of p-anisaldehyde(AA)with both the oleophilic methoxy group and the hydrophilic aldehyde group as additives.AA was completely volatilized during the spinning coating of the active layer with no residue,which means that AA as an additive will not affect the stability of all-PSCs.It is found that AA can affect the aggregation of polymers in the active layer,so that the active layer can form better network interpenetrating structure and more uniform phase separation,which can promote exciton dissociation and charge transfer.In addition,since AA has both oleophilic and hydrophilic groups,AA can not only improve the interface compatibility between donor and acceptor,but also improve the exciton dissociation efficiency at the donor-acceptor interface.It can also improve the interface compatibility between PBDB-T:N2200 layer and hole transport layer,reduce interface contact resistance and promote carrier transfer.At the same time,AA as an additive increased the PCE of the device from 6.29% to 7.24%.The fourth chapter studies the differences in device performance caused by different molecular weights of different batches of N2200 in all-PSCs based on the PBDB-T: N2200.In this study,all-PSCs based on PBDB-T:N2200 were prepared by using N2200 with different molecular weights as acceptors.It was found that the PCE(6.08%)ratio of the devices prepared by the higher molecular weight N2200 was relatively higher than that of the devices prepared by the lower molecular weight N2200(5.81%).It was found that compared with the all-PSCs prepared by the lower molecular weight N2200,the all-PSCs prepared by the higher molecular weight N2200 could not only make the blend layer form a more uniform and fine fiber structure,but also promote the charge collection and exciton dissociation,improve the mobility of the device.In this paper,it was found that adding IDIC as the third component to the PBDB-T:N2200 system,adding AA as the additive to the PBDB-T:N2200 system,and using N2200 with high molecular weight as the acceptor of PBDB-T:N2200,all these methods will improve the performance of all-pscs based on All these methods will improve the performance of all-PSCs based on PBDB-T:N2200. |
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