Design,Synthesis And Application Of Narrow-bandgap Organic Semiconductors Containing Benzotriazole And Benzoprazine

With the development of materials science,organic semiconductor materials have shown broad application prospects in organic photovoltaic cells,field-effect transistors,organic light-emitting diodes,organic sensing,biological diagnosis and treatment due to their abundant sources,tailorable chemical structures,and unique optical,electrical,and magnetic properties.The chemical structure and physicochemical properties of organic semiconductor materials directly determine their application research in different fields and also affect their performance differences in different applications.Therefore,developing high-performance organic semiconductor materials and exploring the relationship between material structure and performance have been a current research hotspot.This dissertation focuses on the related research work of benzotriazole and its derivative units,starting from the design of donor-acceptor（D-A）type molecular,and adopts the molecular design strategy of“extendingπ-conjugate backbone”.A variety of new organic semiconductor materials were designed and developed.The as-synthesized materials have been successfully applied to organic solar cells as well as biological diagnosis and treatment to explore the relationship between structure and performance.In chapter 2,based on benzotriazole as the central building block,a cyanoindanone-modified benzotriazole-fused small molecule monomer was synthesized by extendingπ-conjugate backbone and long alkyl side chain regulation,and a new polymer acceptor material PS1 with a fused-aromatic-ring structure was successfully constructed by using D-A type copolymerization strategy.The solubility,photophysical properties,and energy levels of the polymer PS1 were systematically studied.The results showed that PS1 had good solubility in non-halogenated solvent 2-methyltetrahydrofuran（2-Me THF）,and when combined with the donor material PTz BI-o F,the donor-acceptor materials exhibited complementary absorption spectra and matching energy level structures.This dissertation also investigated the effects of halogenated solvent CF and non-halogenated solvent 2-Me THF as active layer processing solvent on device performances.The results indicated that the devices processed with 2-Me THF exhibited superior charge transport properties,better surface morphology,and ordered molecular packing,with an optimized power conversion efficiency（PCE）of 13.8%.In chapter 3,molecular engineering strategy was adopted,two non-fullerene fused-ring electron acceptors QIP-4F and QIP-4Cl were designed and synthesized by using the imide-functionalized quinoxaline as the central building block and the cyanoindanone modified by fluorine（F）or chlorine（Cl）atoms as end-capping groups.The effects of heteroatom substitution on the photophysical properties,energy levels,and photovoltaic performance of fused-ring electron acceptors were systematically studied.The results showed that both materials exhibited similar absorption profiles,strong intramolecular charge transfer effects and molecular aggregation behavior,as well as relatively deep HOMO energy levels（～5.75e V）.By pairing with polymer donor P2F-EHp,the optimized device based on P2F-EHp:QIP-4Cl achieved a high PCE of up to 13.30%,which is currently the highest reported value for binary polymer solar cells using quinoxaline-acyl-imine fused-ring electron acceptors as active layers.In chapter 4,the molecular design strategy of“extendingπ-conjugate backbone”was used,on the basis of the weak electron acceptor pyrrolo[3,4-f]benzotriazole-5,7-dione（TZBI）,a thiazole-fused quinoxalineimide monomer（QIA）with strongly electron-withdrawing characteristics was firstly designed and synthesized by introducing of a pyrazine heterocyclic unit.And a narrow band gap semiconductor polymer PQIA-BDTT was successfully constructed by introducing QIA moiety into conjugated polymer.Using the amphiphilic triblock copolymer F-127 as the encapsulation material,multifunctional phototheranostic nanoparticles PQIA-BDTT NPs with uniform and controllable size were prepared.The photophysical properties,biocompatibility,and photothermal properties of the nanoparticles were systematically studied.The results showed that the nanoparticles exhibited strong NIR-II absorption and emission characteristics,high extinction coefficient(20.01 L g^–1 cm^–1),excellent photostability,and biocompatibility.When the nanoparticles were irradiated with a laser(1064 nm,1.0 W cm^-2)for 6 min,a photothermal conversion efficiency of up to 72.6%was achieved.In addition,the fluorescence imaging and anti-tumor efficacy of the nanoparticles in vivo were also studied.Studies have shown that after injecting the nanoparticles PQIA-BDTT NPs into tumor-bearing mice via the tail vein,the tumor sites of the mice exhibited strong NIR-II fluorescence signals,indicating that the nanoparticles could effectively accumulate in the tumor tissue.Furthermore,the nanoparticles exhibited excellent anti-tumor efficacy and successfully achieved fluorescence imaging guided photothermal therapy under NIR-II laser irradiation.This work provides a new design concept for constructing a novel NIR-II multifunctional theranostic platform.In chapter 5,based on the design strategy of“extendingπ-conjugate backbone”,a triazole quinoxaline-fused acenaphthenoquinoimide acceptor unit with a larger conjugated skeleton was designed and synthesized by fusing strong electron-deficient acenaphthenoquinoimide unit to the triazole quinoxaline unit.A new polymer semiconductor material PAQI-TT using a D-A type copolymerization strategy was successfully constructed.The multifunctional phototheranostic nanoparticles PAQI-TT NPs with uniform and controllable size were prepared by using the amphiphilic triblock copolymer F-127 as the encapsulating agent.The photophysical properties,biocompatibility,photothermal properties fluorescence imaging in vivo,and anti-tumor efficacy of the nanoparticles were systematically studied.The results showed that the nanoparticles exhibited a wide absorption profile（300-1000 nm）,a NIR-II fluorescence spectrum with a tail extending to 1400 nm,as well as excellent photostability and biocompatibility.Under laser irradiation(808 nm,1.0 W cm^-2)for 8 min,the nanoparticles showed a high photothermal conversion efficiency of up to 80.1%.Meantime,the nanoparticles also exhibit enhanced NIR-II fluorescence signals and significant anti-tumor effects in vivo tumor-bearing mice,and can be used as multifunctional phototheranostics agent.