The Fine Modulation Of Photoelectric Performance For Wide-bandgap Polymers Based Benzodithiophene-4,8-dione(BDD)

The topic that people take advantage of explorative energy and reduce the energy consumption more effectively is talkative in the circle of current society,which new energy prevails and becomes popularization.Meanwhile,solar energy wears the crown among the available energy,leading the area containing majority of the available,and the aspiration of scheduling and further improving the efficiency for solar cells is being studied and focused on by the groups of who research photovoltaic devices.With the development of solar cells,the silicon-based solar cell is still the host of this market,but the undeniable deficiencys are still discussed by others:the higher cost on the processing of manufacture,the huger room for placement and so on.Finally,they hardly apply into popularization widely.And the property of polymer solar cells,such as,flexible structure,lower cost and little damage to environment,are increasingly becoming the mainstream.The promising industralization located on the arena of polymer solar cells in the future.The transition from fullerene to non-fullerene is a remarkable step for the development of polymer solar cells,and nowadays,the highest power conversion efficiency（PCE）of polymer solar cells that entitled in the laboratory has reached the value of 18.6%.The optical absorbance sit in the short wavelengths is still weak for bulk heterjunction solar cells when we select non-fullerene as the main acceptors,so the design and synthesis for wide-bandgap donors gets the popularity among all kinds of researchers.The PM6-based wide-bandgap polymers′PCEs for the device have been gradually stepped over the threshold of 17%.The fine modulation on the general wide-bandgap polymer is mainly via the introduction of electron-deficient units and/or electron-rich units,and the substitution for original groups.The highest occupied molecular oribital（HOMO）and/or the lowest unoccupied molecular oribital（LUMO）level of the virgin materials are modulated by these means.However,the optimization of device performance and the attainment of energy loss are placed on both sides of the balance.Thus,in chapter three,I select（triisopropylsilyl）ethynyl（TIPS）group possessing powerful electron-withdrawing ability linked to the lateral for benzo[1,2-b:4,5-b′]dithiophene（BDT）as electron-rich unit and benzo[1,2-c:4,5-c′]dithiophene-4,8-dione（BDD）as electron-deficient unit,synthesizing a novel donor-acceptor（D-A）type wide-bandgap polymer PTIPS-BDD.The HOMO level of material deepens obviously to-5.64 e V after the modulation of TIPS group.The performance of it still lagged much compared to general polymer blending with non-fullerene acceptor,but its superior charge transfer could rival with those common polymer solar cells.The useness of this potential wide-bandgap donor will become commonplace one day.In chapter four,copolymers or random polymers PM6-x TIPS come true by copolymerizations between PM6 and PTIPS-BDD for the introduction of TIPS group could finish the modulation of virgin material,higher open-circuit voltage(V_OC)and lower energy loss.The fine modulations for the property of random polymer are realized by the different amounts of TIPS groups,we further characterized device performance of them,understanding variation of value for V_OC in device.The simplicity of synthesizing binary copolymers and effective modulation of their physical prpertys lead to the finial values showing photovoltaic performance are 0.86 V(V_OC)and 11.73%（PCE）whose active layer is the blend between random polymer PM6-5TIPS and acceptor IT-4F.It is worthy that chapter five that I focus on a question whether wide-bandgap polymer possessing lower energy loss and higher charge transfer could further showing superior carrier transfer and device performance when it is in ternary solar cells.With different weight ratios of polymer PTIPS-BDD doped in binary blend,the performances of ternary non-fullerene polymer solar cell achieved better tendency compard with binary one.Especially,the type of carrier recombination existed in device are studied in this chapter,and basic concepts on recombination and its characterization in device are also in.The third component polymer PTIPS-BDD doped properly in binary blend own the phenomena that monomolecular recombination decreased slowly and the frequency for bimolecular recombination appearing at the interface of the D-A heterjunction reduced.The initial traps and defects sat in binary blend were filled with the help of polymer PTIPS-BDD,and the PCEs for ternary device are12.34%and 16.21%after doped in blend based on PM6/IT-4F and PM6/Y6 binary one,maximizing their excellent charge transfer.