Study On All Polymer Organic Solar Cells

Polymer solar cells(OSCs)owns the advances of light-weight,flexible,and preparation in larger area.Up to now,the efficiency of the OSCs have over to 18%.At the same time the efficiency of all polymer solar cells(AOSCs)have reached to 11%.As known to as,the devices of the AOSCs have the obvious advantages in stability of thermodynamics and mechanical,which makes it a research hotspot and will have important significance for promoting the commercialization of organic solar cells.This work is mainly aimed at improving the photoelectric conversion efficiency(PCE)of all-polymer organic solar cells.On the one hand,it is an attempt to introduce polymer acceptors and donors with asymmetric structures into all-polymer battery systems in order to achieve the effect of improving device performance.On the other hand,try to optimize the performance of the polymer by modifying the side chain of the polymer.At the same time,through the preparation of organic solar cell devices in this process,the influence of the preparation process on the final efficiency of the device was recognized.The specific content can be divided into the following three aspects:(1)An asymmetric structures polymer,PBDTβNPDI,was designed and synthesized.It presents a strong optical absorption in the spectral region of 300-600 nm,in the meanwhile it keep a complementary optical absorption with donor polymer PTBTz-2 in visible and near infrared region.The morphology of the organic active layer based on PTBTz-2: PBDTβNPDI was significantly improved after annealing and adding DIO as an additive,and the degree of phase separation and crystallinity were improved.At the optimal condition the PCE of the devices based on PTBTz-2: PBDTβNPDI reached to around 6.14%.It demonstrated that the polymer acceptor with asymmetric structure could be utilized to preparation high efficiency AOSCs.(2)Two kind of polymer donors with same structures was designed and synthesized named PTBD-BZ and PTBD-Cl-BZ,both of them with asymmetric structure,and present obvious π-π conjugation in the film.Two kinds of AOSCs based on acceptor N2200 was preparation.After optimal the PCE of the devices based on PTBD-BZ: N2200 reached to 6.3806%,and the PCE of the devices based on PTBD-Cl-BZ: N2200 reached to 3.0816%.The reason why the devices based on the donor polymer with similar structure have different efficiency is that these two donor have different absorption strength.(3)In order to weaken the strong aggregation of the N2200,we try to use the method of random copolymerization to optimize the side chain of polymer N2200,and synthesized a novel polymer acceptor named PNDIOD-30 Se.The study found that the absorption spectrum of PNDIOD-30 Se is about the same as that of N2200.At optimal condition the PCE of the devices based on PTBD-BZ:N2200 was over to 6.42%,in the meanwhile the fill factor of this devices also improved nearly 5%.The results show that the aggregation ability of polymer receptors is weakened to some extent after random copolymerization.This provides an idea for the improvement of polymer structure.