The Design,Synthesis And Photovoltaic Applications Of Wide Band-Gap Polymer And Asymmetic Non-Fullerene Small-Molecule Acceptors

The active layer is an important component of organic solar cells,and the active layer is mainly composed of a mixture of acceptors and donors.the best combination of efficiency is band-gap polymer donors and narrow band gap acceptor small molecules.The power conversion efficiency has breakthrough 18%.The main reason is(a)broadband polymer donors can obtain lower highest occupied orbital energy levels(HOMO)energy level,which effectively obtains a higher open circuit voltage(V_oc);(b)The absorption of the donor and acceptor produces a better complementarity,thereby absorbing more photons and obtaining a high short-circuit current density(J_sc).The research content of this paper is based on chlorinated two-dimensional band-gap polymer donor materials and asymmetric nuclear acceptor small molecule acceptor materials,synthesized a series of chlorinated donor polymers and asymmetric acceptor small molecules,respectively.The introduction of different numbers of chlorine atoms affects the polymer donor and the introduction of different alkyl side chains in the asymmetric core framework on the properties of acceptor small molecule materials.1.We use benzodithiophene(BDT)as the group,introduce different numbers of chlorine atoms into the alkoxy phenyl conjugated side chain to form a donor unit,and difluorobenzotriazole(FBTZ)as the acceptor The wide band gap two-dimensional conjugated polymer donors(DZ1,DZ2 and DZ3)of the unit,and the fused ring acceptor derivative Me IC as acceptor materials were used to prepare high-Efficiency non-fullerene polymer solar cells(NF-PSCs).The three polymer donors DZ1,DZ2 and DZ3 showed similar absorption spectra in the range of 300-700 nm,and the optical band gaps(E_g^opt)were 1.84,1.92 and 1.97 eV,respectively.Compared with DZ1without chlorine substitution reported in the literature,it is found that the introduction of chlorine atoms at the meta position of the alkoxy phenyl group makes the polymer have a lower HOMO energy level,thereby increasing theV_oc of PSCs and improving the hole mobility.Compared with PSCs based on DZ1:Me IC(8.26%)and DZ3:Me IC(6.28%),non-fullerene PSCs based on DZ2:Me IC have a V_oc of 0.88 V,a J_sc of 17.62mA·cm^-2,and a fill factor(FF)It is 68%,and the photoelectric conversion efficiency(PCE)of 10.22%is obtained.The results show that adjusting the number of chlorine atoms on the side chain of polymer alkoxy phenyl is a promising way to construct high-performance PSCs donor materials.2.Inspired by the Y6 molecule,we designed and synthesized small non-fullerene receptor molecules ASY1 and ASY2 with asymmetric electron-deficient core A'-DAD-A'structure.We found through the ultraviolet absorption test that the two acceptor molecules have good absorption at 500-900 nm,and the TGA test shows that the two small molecules have good thermal stability.