Design, Synthesis And Electron Devices Properties Study Of Boron And Nitride Doped π Conjugated Structures

Compared with traditional inorganic semiconductors,solution-processable organic semiconductor materials have attracted many attentions in recent years due to their advantages of light weight,low cost,and ease of processing.Although organic semiconductors have these advantages,the performance ultimately exhibited in electronic devices has yet to be improved.In order to obtain high electron and hole mobility in field effect transistors,it is often required that the conjugated skeleton of the P-type or N-type material has good planarity and π-π stacking.In organic photovoltaic devices,the power conversion efficiency is mainly proportional to the product of three parameters of short-circuit current,open circuit voltage,and fill factor.In order to obtain higher power conversion efficiency,it is required that the donor and acceptor materials have good light absorption ability and matched energy levels in addition to good planarity and π stacking.In this way,on the one hand,the energy of the sun can be maximized,and on the other hand,the matched energy levels can also provide sufficient driving force for the separation of excitons.At the same time,in the preparation of bulk heterojunction solar cells,the donor and acceptor blend membranes need to form a good phase separation structure,thereby obtaining a higher fill factor.These problems can be regulated by the molecular structure of organic semiconductors.Therefore,designing new organic semiconductor materials and tailoring the structure to regulate its device performance is a hot research topic.The most mainstream method for constructing organic semiconductor materials is to covalently connect the electron-rich unit(D)and the electron-deficient unit(A).In this study,we design novel conjugated semiconductor materials from two aspects based on molecular engineering principles.On the one hand,the existing classical A-unit pyrrolopyrroledione(DPP),thiophene imide(TPD)and benzothiadiazole(BT)were selected,and a series of AA-type conjugated organic small molecules were obtained by covalent attachment.They were applied to field effect transistor research.O n the other hand,a novel A-unit was designed by introducing a boron(B)electron-deficient center into the conjugated skeleton for constructing a novel conjugated material.In order to investigate the effect of the coordination of boron and nitrogen on the polymer level and band gap,we designed two polymers containing pyrazine to reduce the energy levels and bandgaps of polymerization by coordination with Lewis acid,namely tripentafluorophenylboronic acid.Furthermore,the B-deficient electron center was introduced into the conjugated framework to make it a part of the conjugated structure,and a novel A-unit BNIDT was obtained.The difference in photoelectric properties between this unit and its full-carbon skeleton IDT unit was systematically studied.At the same time,the bromine atom was introduced into the BNIDT unit,and the effect of the bromine atom substitution on the photoelectric properties was studied.Studies have shown that BNIDT is a conjugated unit with strong electron-deficientity and has broad application prospects in the construction of novel organic conjugated semiconductors,especially organic solar cell receptor materials.