Study On The Synthesis And Photovoltaic Performance Of BDT-halogenated Aromatic Donor Materials

In recent years,due to the promotion of green production and lifestyle,solar energy,a sustainable clean energy source,has become a research hotspot.The use of solar energy to develop the photovoltaic industry is of great significance to improving environmental issues.Organic solar cells have the advantages of low cost,light weight and thinness,easy large area preparation,easy curling,etc.,which provide the possibility for device production.At present,the relatively mature bulk heterojunction organic solar cells(BHJ-OSCs)have a photoelectric conversion efficiency of over 18%.The design and synthesis of new donor materials has opened up a feasible way to improve the photoelectric conversion efficiency of devices.In this paper,aiming at the optimization of organic solar cell donor materials and device process,a series of low-cost aromatic donor materials are designed and synthesized.The materials are studied by regulating the type,position and quantity of halogen substitution effect(F and Cl atom substitution).Further study the relationship between the photophysical properties,electrochemical properties,charge transport properties and photovoltaic characteristics of the materials.The obtained materials are applied to devices based on fullerene acceptor PCBM and non-fullerene IDIC to explore the optimal device preparation process.The main research work is as follows:(1)The first chapter of this paper is a brief introduction to the application of organic solar cells and donor materials based OSCs.The good photoelectric properties of halogen-substituted donor materials make it a research hotspot in the design of donor materials.A series of halogen-substituted polymer donor materials were synthesized by designing experimental schemes of halogen substitution strategies with different number of fluorine and chlorine atom.The second chapter of this thesis introduces the preparation methods of the experimental instruments,reagents and devices used in the experiment,and further introduces the means of characterizing the photoelectric properties of materials.(2)In Chapter 3 of this thesis,four polymer donor materials of D-A type with BDT as D unit and fluorophenylene as A unit were synthesized through a one-step reaction.On this basis,the?bridge(thiophene unit)was introduced into the backbone of the molecule,and D-?-A-?type polymer donor materials P1F-T,P2F-T and P4F-T were obtained.Through a series of characterization of the material,the influence of fluorine substitution effect on the photoelectric properties of the donor material's molecular configuration,molecular energy level and absorption spectrum was studied.The donor material was further applied to the device based on the fullerene PC₇₁BM acceptor can achieve the good morphology of the active layer,good power conversion efficiency(PCE)of OSCs.(3)On the basis of the fluorine-substituted polymers,Chapter 4 of this thesis further study the effect of chlorine substitution.Two polymer donor materials P1Cl-T and P2Cl-T based on thiophene-chlorobenzene-thiophene monomer were designed and synthesized.The introduction of thiophene units and chlorine atoms well adjusts the planarity of the basic skeleton and significantly reduces the molecular energy level of the polymer donor material.Further research on the relationship between the photoelectric properties of the material and the photovoltaic properties of the device,it is found that the same chlorine substitution effect can also increase the Voc by reducing the HOMO energy level.In addition,the PCE of the device can be significantly improved by optimizing the process of preparing the active layer.(4)Organic donor materials include not only polymer donor materials based on OSCs,but also p-type hole transport materials(HTM)based on perovskite solar cells.In Chapter 5,we designed and synthesized the aromatic diphenylamine compound Cz-3OMe TAD based on the carbazole unit as the central core.The asymmetric Cz-3OMe TAD obtained has a"three-wing propeller-like"molecular structure,which can be tilted through a highly twisted configuration to form a weak Intermolecular interaction can achieve good hole transport performance.The asymmetric Cz-3OMe TAD material was applied to the device as the HTM material of the perovskite solar cell,and the optimal PCE was 16.36%.The material has an appropriate energy level and relatively high mobility,and exhibits good solubility in organic solvents,and is suitable for solution processing to prepare devices.