| Highly conductive carbon films have widespread application,especially in the electric heating devices,energy storage devices,and solar cells.At present,the research of high-conductivity carbon film mainly focused on graphene film and graphdiyne film,but the well-structured and excellent performance graphene films and graphene films require complicated preparation processes and high equipment investment,which cause them difficult to produce widely in industry.Therefore,it is necessary to find a cheap carbon source and a simple method to prepare a highly conductive carbon film.In this paper,high temperature coal tar was used as carbon sources to prepared carbon films on quartz substrate at different condition,and the effect of preparation conditions on the structure and properties of carbon films was studied in detail.Meanwhile,the relationship between coal tar-based carbon film structures and its electrical conductivity and electrothermal performance were also investigated in this paper.Finally,the arene compound and heteroatom compound were used as carbon sources to prepare the carbon films,and the effects of different components in coal tar on the structure and properties of carbon film were simulated and investigated.The performance analysis results of carbon films show that carbonization time,coal-tar added amount,and carbonization temperature all affect the electrical and electrothermal properties of the carbon films.And the carbon film can be controlled preparation by changing the preparation parameters?such as carbonization time,carbonization temperature and coal tar addition?.Extending the carbonization time can effectively reduce the resistivity and sheet resistance of the carbon films and improve the electrothermal performance of the carbon films.The resistivity of carbon films decreased from 1.34×10-33 Ohm·cm to 6.96×10-44 Ohm·cm and the sheet resistance of carbon films decreased from 1312.7 Ohm/sq to 793.0 Ohm/sq,and the maximum heat generation temperature of carbon film under 30 V can reach to 88.9°C.Increasing the amount of coal-tar added amount also changed the resistivity and sheet resistance of carbon films.The resistivity of carbon film increased first and then decreased with an increase in coal-tar added amount,the lowest resistivity was 6.42×10-44 Ohm·cm.The sheet resistance and electrothermal performance of carbon films decreased with an increase in coal-tar added amount,and the sheet resistance decreased from 793.0 Ohm/sq to 108.2 Ohm/sq and the maximum heating temperature of carbon film under 30 V can reach to 174°C.Carbonization temperature is one of the most main factors,and it significantly affects the conductivity of carbon films.Increasing the carbonization temperature can significantly reduce the resistivity and sheet resistance of carbon films and improve the electrothermal performance.The resistivity of carbon films decreased significantly from 8.9×10-22 Ohm·cm at 700 oC to 7.07×10-44 Ohm·cm at 1100 oC and the sheet resistance of carbon films decreased from 1.07×105 Ohm/sq to 296.1 Ohm/sq,and the maximum heating temperature of carbon films under 30 V can reach to 127°C.Structural characterizations of carbon films showed that changing the preparation conditions of carbon films can affect the graphitization degree of carbon films,and also can change the carrier concentration and mobility in the carbon film.The coal tar based carbon film had a large carrier concentration in the range of 1021-1022/cm3,and the mobility generally less than 1 cm2/Vs.The carrier concentration in the carbon film gradually increases with an increase in carbonization time and the maximum carrier concentration was 4.6×1022/cm3,while the carrier mobility decreased with an increase in carbonization time and the minimum carrier mobility was 0.17 cm2/Vs.The coal-tar added amount also affects the graphitization degree,the carrier concentration,and the mobility of carbon films,but it does not show a clear change rule.Increasing the carbonization temperature significantly increases the graphitization degree of carbon films and enhances the conductivity of the carbon films,but there was no clear change rule in the carrier concentration and its mobility.The results of the performance and structural characterization of carbon films prepared from different carbon sources showed that the type of carbon source has a great influence on the conductivity and electrothermal properties of the carbon film.The electrical resistivity and sheet resistance of the arene-based carbon film are lower than that of the coal tar-based carbon film.The conductive and electrothermal properties of naphthalene-based carbon film are the best and its resistivity and sheet resistance were 6.4×10-44 Ohm·cm and 43.4 Ohm/sq,respectively.Naphthalene-based carbon film exhibits excellent electrothermal performance and its maximum heat generation temperature at 30 V exceeds 300 oC.For the heteroatom-based carbon film,the resistivity of p-hydroxybiphenyl-based carbon film was slightly smaller than that of coal tar-based carbon film while the resistivity of pyridine-based and benzothiophene-based carbon film was higher than that of coal tar-based carbon film.The types of heteroatom have a different influence on the conductivity of the carbon film,and addition of oxygen to toluene reduced the resistivity of toluene-based carbon film while addition of nitrogen and sulfur increased the resistivity of toluene-based carbon film.Different structure of carbon sources affect the graphitization degree of carbon film and change the carrier concentration and its mobility.The presence of heteroatoms compounds in carbon sources increased the carrier concentration of the carbon film?all higher than 1×10-44 Ohm·cm?,but reduced the carrier mobility of the carbon film?all lower than 1 cm2/Vs?. |
PDF Full Text Request