Simple Polymer Donor Materials Based On Different Catalysts And Ferroelectric Polymer Addition Improve The Performance Of Organic Solar Cell

Organic solar cells（OSCs）stand out among many solar cells because of their unique advantages such as light weight,flexibility and translucency,and have become a hot research object at present.Although the efficiency of high-efficiency organic solar cell is close to 20%at present,due to expensive active layer materials and complex coating process,there is still a big gap from the true sense of industrialization.It means that simpler structured photoactive layer materials and simple device optimization processes are crucial for OSCs.In this article,my research focuses on the optimization of device performance through simple donor material design and inexpensive ferroelectric polymer additives.In response to the uneven mixing of donor and acceptor materials in bulk heterojunctions due to differences in solubility,as well as the erosion of lower layer donors during layer-by-layer deposition,two A1-A2 type polymer donors PBTz-TC and PBTz-TTC were selectively synthesized by combining benzotriazole（BTz）units with monoester thiophene.This combination allows for a longer exciton dissociation region at the active layer donor-acceptor interface while maintaining the high crystallinity required for bilayer devices,thus facilitating higher short-circuit current density and fill factor.Therefore,OSCs with PBTz-TC/IT-4F as the active layer can achieve a high-power conversion efficiency of 11.96%and a high short-circuit current density of>20 m A cm^-1.Moreover,we have also studied the differences in molecular weight,optical properties and crystallinity caused by catalyst selection in depth,using PBTz-TC as an example.This also provides a direction for the selection of catalysts in the synthesis of optoelectronic polymers in the future.In response to the important but little-received issue of enhancing the built-in electric field to facilitate the charge transfer process,and explore the introduction of inexpensive ferroelectric polymer polyvinylidene fluoride（PVDF）as an additive into the active layer of non-fullerene OSCs to optimize internal charge dynamics and improve device performance.The induced electric field generated by ferroelectric dipole polarization helps facilitate exciton separation and carrier transport,reduce charge recombination,and fine-tune morphology in the active layer.In addition,it has good results in multiple systems,PM6:Y6-baced OSCs achieved a record 17.72%efficiency,and OSC with PM6:BTP-e C9 as the active layer also achieved an excellent efficiency of 18.17%.Ferroelectric polyvinylidene fluoride（PVDF）was further used to improve the comprehensive performance of large-area organic solar cell.The addition of PVDF enhances the construction of internal electric field and promotes charge kinetic processes.Moreover,the strong interaction and chain entanglement between the polymer feeder and PVDF can form a strong polymer network,which effectively protects the active layer from excessive washout/swelling between D/A components and induces favorable vertical phase distribution.This good promoting effect is also beneficial for the scraper coating printing of green solvents,improving the efficiency and stability of the device,and enhancing the mechanical flexibility of the device.Due to the multiple advantages of PVDF,LBL devices based on PM6/BTP-e C9 achieved a high efficiency of 18.35%.By using green solvent for scraper coating printing,the efficiency of large area（1.21 cm²）secondary components reached 16.40%.In particular,the polymer network of PVDF improves both fracture strength and tensile strain,giving the active layer material higher toughness,and even allowing small molecule-based systems to have mechanical flexibility and comprehensive performance comparable to all-polymer systems.