Design,Synthesis And Photovoltaic Properties Of Water/Alcohol-soluble Conjugated Small Molecules/Polymers Based On Ethynyl

Polymer solar cells(PSCs)have been extensively investigated due to their intrinsic advantages including light-weight,flexibility,all-solid,low-cost solution processing techniques.Recently,rapid improvements have been made in the performance of bulk heterojunction(BHJ)PSCs with power conversion efficiencies(PCEs)over 12% via the new design of the donor/acceptor materials,optimization of morphology and device configuration engineering.Besides,the interface engineering with new hole/electron transport layers(HTLs/ETLs)is also extremely essential for maximizing the performance of PSCs,which is important to control the energy level alignments between different layers,enhance charge selectivity and extraction at the electrodes.Varieos functional polymers can be obtained by different polymerization via monomers based ethynyl.Moreover,the introduction of triple bonds as linking groups in conjugated small molecules/polymers can reduce the steric hindrance,expand the conjugated plane,produce more closer stacking,which may improve the charge transport property of congated small molecules and polymers.Therefore,we have developed serieses of water/alcohol-soluble conjugated small molecules/polymer based on ethynyl as ETLs for PSCs.In chapter 2,we prepared a series of water/alcohol polymers by ‘click' polymerization,Sonogashira polymerization and Glaser-Hay polymerization,respectively,through the monomers with ethynyls as terminal groups.These polymers possess the same conjugated groups but different connection units in the backbones.The properties of the polymers can be regulated by the different connection units resulting from different polymerization reactions.These functional water/alchol-soluble conjugated polymers could be applied as ETLs in PSCs to improve the performance of photovoltaic devices.In chapter 3,two naphthalene diimide(NDI)and perylene diimide(PDI)based n-type water/alcohol soluble small molecules(NFN and PFP)are designed and utilized as ETLs for PSCs.Synthesized via Sonogashira coupling,NFN and PFP show excellent planarity,higher thermal stability and obvious self-doping behaviors.NFN and PFP can be used as an excellent electron transport material for PSCs.While,the PCE of PFP based photovoltaic device can be 9.8%,higher than that of NFN based devices,is originated from the stronger doping property and higher mobility of PFP.And devices with 60 nm of PFP showed a moderate PCE of 6.79%.In chapter 4,we aimed to design and synthesize a series of self-doped n-type water/alcohol-soluble conjugated polymers containing fullerenes,as ETLs with higher mobilities for PSCs.Exploring to the synthesis of the designed polymers through Suzuki polymerization and Sonogashira polymerization,we found that the polymers containing fullerenes can be obtained via Sonogashira polymerization but with poor solution processability as the solubility of these polymers was rapidly reduced in a short time in the solid state,possibly,result from the interaction between fullerenes and the amine groups contained in the polymers as well as the strong stacking of the polymer in the solid state.