Study On The Synthesis And Properties Of Donor Materials Based On Benzothiadiazole And Its Derivatives

Making full use of clean and renewable solar energy plays a vital role in saving energy,protecting the environment and alleviating the global energy crisis.As a strong electron-withdrawing group,benzothiadiazole has a wide range of applications in both donor and acceptor materials,and has achieved good results.In the second chapter of this paper,two acceptor units were synthesized by stille coupling reaction based on benzothiadiazoles with different alkyl chains as the core and thiophene as the bridge,and added to the copolymerization system of W1 and two-dimensional BDT to synthesize two random Copolymers(P1 and P2).The thermal decomposition temperatures of P1 and P2 are 352℃ and 370℃,respectively.The absorption range of the P1 in film state is from 300 nm to 710 nm,and it has good absorption in the visible light region.The absorption sideband is 680 nm,and the optical band gap of the polymer P1 is 1.82 eV.The light absorption range of P2 in film state is 300 nm to 681 nm,the absorption sideband of is 677 nm,and the optical band gap of P2 is 1.83 eV.The HOMO energy level of P1 is-5.48 eV,the LUMO energy level is-3.54 eV,and its electrochemical band gap is 1.94 eV.The HOMO energy level of P2 is-5.49 eV,the LUMO energy level is-3.49 eV,and its electrochemical band gap is 2.00 eV.Finally,organic solar cells(OSCs)device were fabricated by blending with Y6 as an active layer.The highest energy conversion efficiency(PCE)of P1 was 14.33%,and the highest energy conversion efficiency of P2 was 14.57%.In the third chapter of this paper,two simple copolymers(P3 and P4)based on benzothiadiazole with different alkyl chain as A unit and thiophene as D unit was synthesized by stille coupling reaction.The thermal decomposition temperatures of P3 and P4 are 330 ℃ and 306 ℃,respectively.The absorption range of P3 in the film state is from 300 nm to 826 nm,its absorption sideband is 775 nm,and the optical band gap is 1.6 eV.The absorption range of P4 in the film state is from 300 nm to828 nm,and its absorption sideband is 769 nm.and the optical band gap is 1.61 eV.The HOMO level of P3 is-5.45 eV,the LUMO level is-3.54 eV,and the electrochemical band gap is 1.91 eV.The HOMO energy level of P4 is-5.51 eV,the LUMO energy level is-3.56 eV,and the electrochemical band gap is 1.95 eV.Finally,organic solar cells(OSCs)device were fabricated by blending with Y6 as an activelayer.The highest energy conversion efficiency(PCE)of P3 was 7.43%,and the highest energy conversion efficiency of P4 was 6.58%.In the fourth chapter of this paper,two polymer donors(P5 and P6)were synthesized by stille coupling reaction.The optical band gap of P5 is 1.92 eV.The HOMO energy level is-5.52 eV,the LUMO energy level is-3.66 eV,and the electrochemical band gap is 1.86 eV.The optical band gap of P6 is 1.93 eV.The HOMO energy level is-5.44 eV,the LUMO energy level is-3.68 eV,and the electrochemical band gap is 1.76 eV.Finally,organic solar cells(OSCs)device were fabricated by blending with N3 as an active layer.The highest energy conversion efficiency(PCE)of P6 was 10.00%,and the highest energy conversion efficiency of P6 was 13.51%.