Preparation And Properties Of Organic Conjugated Semiconductor Materials Based On Fluorene Unit

Conjugatedpolymersemiconductormaterialshavebeenstudied comprehensively in photovoltaics,catalysis,gas adsorption,and medicine.Fluorene is a very important conjugated ring compound,because it is relatively stable to heat,acid and alkali,and it has a rigid main chain,which is favorable for intramolecular electron transport.It can be applied in many fields such as photoelectricity,catalysis,gas adsorption,and supercapacitors.and more importantly,the fluorene and its derivatives are susceptible to change the structural modification.In this work,the effect of the introduction of fluorine atom on benzothiadiazole on the photocatalytic activity of hydrogen production from polymer semiconducting materials was studied using ethyl trimeric fluorene as the main structural unit.The methyltrimeric fluorene was separated to reflex from benzene and biphenyl which can discuss the effects of different chain length on the photocatalytic hydrogen production The methyl fluorene was combined with quinoxaline and benzoselenazole,and different narrow bandgap units were studied for polymer semiconductor materials.to get the effect of photocatalytic energy;benzothiadiazole was combined with fluorenone and dibenzothiophene to study the effect of different substituent units on the photocatalytic properties of polymer semiconductor materials.The main conclusions are as follows:1.Two conjugated polymer networks were synthesized by the Suzuki-Miyaura cross-coupling reaction of ethyl truxene and two benzothiadiazole monomers.Polymer Tr-BT and Tr-FBT were explored for photocatalytic hydrogen production from water.The effects of fluorine substitution on the optical band gap and photocatalytic performance were investigated.Comparing these two polymers shows that fluorine substitution slightly changes the conjugated structure,enhances the ionization potential,and results in a slight blue shift in UV absorption and an increase in catalytic performance.These indicate that the development of copolymers based on fluorine substitution may be a strategy for improving the performance of organic catalysts.2.Methyl truxene is the main unit,conjugated polymer semiconductors obtained from the polymerization of benzene and biphenyl monomers,and the performance of its photocatalytic water hydrogen production.The effect of the polymer on optical properties and photocatalytic properties was studied.Compared with the P-TR,the polymer DP-TR exhibited a higher hydrogen evolution rate of 9.5?mol h^-11 under ultraviolet and visible light irradiation,which may be due to the change of the chain length.3.By synthesizing linear fluorene conjugated polymers QX-FL and SE-FL,the photocatalytic properties of hydrogen production were tested,and the effect of different narrow bandgap units on photocatalytic performance was studied.The prepared polymers QX-FL and SE-FL have a wide light absorption range,a suitable optical bandgap,and both polymers have the ability to photocatalyze hydrogen production from water.It was found that the modification effect of benzoselenazole group on hydrazine is better,and the narrow banding unit of benzo selenazole group is superior to the quinoxaline unit in the ability to adjust the band gap,which improves the photocatalytic performance of the polymer.The photocatalytic activity of QX-FL was 0.4?mol h^-1,and the photocatalytic activity of SE-FL was 3.5?mol h^-1.4.Two conjugated linear polymers were synthesized by the Suzuki-Miyaura cross-coupling method using two fluorene and benzothiadiazole monomers.The polymer BT-FLO and BT-DBT were explored for photocatalytic water hydrogen production.In this chapter,keto units and sulfone units are introduced into the carbon atom of fluorine in nine position and we design keto units and sulfone units to change the conjugate degree,band gap,and charge carrier transport ability of the polymer which can affect the Catalytic performance.Under natural light??>300 nm?,the photocatalytic activity of BT-FLO is 10?mol h^-1,the photocatalytic activity of BT-DBT is 69?mol h^-1,and the photocatalytic activity of BT-DBT under visible light is 60?mol h^-1,The photocatalytic activity of BT-DBT has a good effect in the visible light??>400nm?range.The two polymers shows that the sulfone unit slightly changes the conjugated structure,enhances the ionization potential,results in a slight blue shift in absorption and a significant change in the catalytic activity,and the sulfone group unit can greatly increase the carrier mobility.These studies indicate that the development of copolymers based on sulfone units may be a new strategy for the development of organic conjugated polymer catalysts.