| Solar energy as an inexhaustible new renewable energy,has been widespread concern in the community,with the human demand for new energy continues to increase.In order to make better use of solar energy to solve the energy crisis and the ecological environment,people began to vigorously develop the solar photovoltaic industry,especially the development of organic solar cells.Organic solar cell material has become a subject of widespread concern because it has the characteristics of light weight,low cost,easy access to raw materials.However,compared to inorganic semiconductor solar cells,the efficiency of organic solar cells is much lower,life is also much shorter,and the application of organic solar cells has been limited.Therefore,in order to improve the efficiency of organic solar cells,the design and synthesis of a comprehensive performance good new organic solar cell donor material is a key breakthrough.Based on the advantages of ternary polymer structure and DPP unit,we propose to construct a series of ternary polymer donor materials based on DPP unit and having a 2A/D or1A/2D structure to obtain a polymer material with excellent light absorption properties,charge transport performance,efficient and stable organic polymer solar cells.(1)In Chapter 3,four random ternary polymers PDPP-Th1-TT1,PDPP-Th2-TT1,PDPP-Th1-TT9 and PDPP-Th9-TT1 are designed and successfully synthesized via Still cross-coupling polymerization by choosing diketopyrrolo[3,4-c]pyrrole(DPP)as acceptor unit,thiophene(Th)and thienothiophene(TT)as donor units.The polymer has good thermal stability.When the weight loss is 5%,the temperatures are 390.5°C,390.5°C,387°C and391°C,respectively.The four polymers both have a broad absorption spectrum between 530 nm and 950 nm.By adjusting the donor acceptor ratio of the four polymers,we can obtaindifferent HOMO levels.The device structure was ITO/PEDOT: PSS/Polymer: PCBM/LiF/Al was prepared by using these four polymers as the donor material and PC70 BM as the acceptor material.In order to find the best solvent system,we optimize the device by changing the solvent system.Then,in the optimum solvent system the device is optimized by changing the ratio of the receptor.After finding the best proportion of the receptor,we are also optimized by changing the annealing temperature,additives and steam treatment.Finally,the organic solar cell conversion efficiency of up to 3.47%.(2)In Chapter 4,two random ternary polymers PDPP-TT1-DPP1 and PDPP-TT1-DPP2 are designed and successfully synthesized via Still cross-coupling polymerization by choosing two different side chains of diketopyrrolo[3,4-c]pyrrole(DPP)as the acceptor unit,thienothiophene(TT)as the donor unit.And then the two materials were tested and analyzed from the optical properties,thermal properties,and electrochemical properties,respectively.By changing the donor acceptor ratio of the two ternary polymers,we have successfully broadened the absorption spectra of the two polymer materials,the spectral range between600-1000 nm.The two polymers has good thermal stability.When the polymer has a weight loss of 5%,the temperature range is between 380-400°C.The polymers have a lower HOMO level.The polymers as an organic polymer solar cell donor material is excellent.(3)In Chapter 5,two random ternary polymers PDPP-B1-DPP1 and PDPP-B1-DPP2 are designed and successfully synthesized via Still cross-coupling polymerization by choosing two different side chains of diketopyrrolo[3,4-c]pyrrole(DPP)as the acceptor unit,Benzene(B)as the donor unit.And then the two materials were tested and analyzed from the optical properties,thermal properties,and electrochemical properties,respectively.We found that the two polymer materials have a very significant absorption band between 600-1000 nm.The two polymers has good thermal stability.When the polymer has a weight loss of 5%,the temperatures are 382.67°C and 385.33°C,respectively.The polymers have a lower HOMO level that making them hopefully become a better donor material for polymer solar cells. |
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