| With the rapid development of organic semiconductors and photovoltaic materials,many high-efficiency organic photoelectric materials have been discovered,and the mechanism of organic photoelectric effects is becoming more clear.Organic photoelectric materials have many advantages,such as expandable molecular structure,adjustable energy bandgap,rich variety of materials,low manufacturing cost,light and flexible.In addition to their applications in organic solar cells（OPV）and organic field effect transistors（OFET）,there is a huge development potential in the field of organic photodetectors（OPDs）with specific spectral response range requirements.As an important component of organic optoelectronic materials,conjugate polymerization can flexibly adjust the energy band and energy level through monomer selection to obtain the required optoelectronic properties.Among them,narrow bandgap is an important development trend.In this paper,the effects of copolymerizating sidechain-modified thienoisoindigo units with classical donor units and homopolymerizating thienoisoindigo units on energy level modification were studied,and the corresponding devices were prepared to study its effect on the photoelectric performance.This work provides some ideas for the modification of the energy level and spectral response range of narrow bandgap conjugated polymers,explores the possibility of using thienoisoindigo polymers in organic optoelectronic devices,and expands the database of narrow bandgap conjugated polymers.The main research contents of this paper are as follows:In chapter One,based on literature research,the types and applications of narrow bandgap conjugated polymers were briefly summarized.In the second chapter,we uses 3-bromothiophene as raw material,through reductive amination,alkylation,etc.to synthesize small molecule thienoisoindigo（TIIG）,and copolymerize with classic donor units,benzodithiophene（BDT）and cyclopentadithiophene（CDT）,by Stille coupling to synthesize two well-regulated donor-acceptor conjugated polymers,poly thienoisoindigo-benzodithiophene（PTIIGBDT）and poly thienoisoindigo-cyclopentadithiophene（PTIIIGCDT）.Study the influence of the change of donor unit on the photoelectric properties such as the energy level and energy gap of the polymer.With the replacement of the donor unit from BDT to CDT,the absorption peak of the polymer red-shift significantly,the spectral response expanded from 1000 nm to 1300 nm,and the bandgap get narrower.In chapter 3,the molecular structure of polyisoindigo（PIIG）were modified,by introducing thiophene units to replace the benzene ring gradually,three narrow bandgap conjugated homopolymers were synthesized,and the influence of quinone structure ratio on the photoelectric performance of the polymer Influence was compared.As the ratio of thiophene units in the polymer increases,the proportion of the quinone structure increases,the optical bandgap gets narrower gradually,and the absorption edge of the polymer undergoes a significant red-shift,which even roughly covers the entire near-infrared spectrum.Due to the low photoelectric conversion efficiency of the classic organic solar cell device based on these polymers,their wide application on organic photovoltaic device is limited.However,these polymers’ excellent infrared spectral response characteristics makes them potential in the application of near-infrared lightresponsive electrical devices. |
