Study On The Charge Transport And Electrical Properties Based On Organic Electronic Devices

With the rapid development of organic electronic,organic semiconductors and electronic devices have been extensively investigated.The electronic devices based on organic materials have the potential to replace the traditional inorganic electronic due to their good properties and potential applications in many fields.However,organic electronic devices also have some defects,which seriously limit the development of organic semiconductors.In order to further develop organic electronic devices,it is necessary to study the properties in organic semiconductor materials and the charge transport in organic semiconductors.Recently,many researchers have studied organic electronic devices,and they also have obtained some important results.But there are still some problems in mobility model.In this paper,the charge transport in organic electronic materials and the applicability of physical models are studied.Some important results are listed as follows:Firstly,hole transport and electrical properties in a high-mobility n-type copolymer N2200 are investigated.It is found that the thickness dependent current density versus voltage?J-V?characteristics of N2200 hole-only devices cannot be well described by using the conventional mobility model.However,the thickness dependent and temperature dependent J-V characteristics of N2200 hole-only devices can be accurately described using the improved extended Gaussian disorder model?IEGDM?.The numerically calculated carrier density is a decreasing function of the distance from the interface and the numerically calculated electric field is an increasing function of the distance from the interface.Both the maximum of carrier density and minimum of electric field appear near the interface.Secondly,the electron transport and electrical properties in N2200 are investigated.It is found that the thickness dependent J-V characteristics of N2200 electron-only devices cannot be well described by using the conventional mobility model.However,the thickness dependent and temperature dependent J-V characteristics of N2200 electron-only devices can be accurately described by using IEGDM only with a single set of parameters.The width of the Gaussian density of states?=.0083eV and lattice constant a=8.0 nm.The width of the DOS is considerably smaller than usually obtained for conjugated polymers,indicating a low degree of energetic disorder and small temperature activation.Furthermore,too large or too small values of the boundary carrier density lead to incorrect J-V characteristics.Then,an analysis of the layer thickness and temperature dependence of the current density in hole-only devices based on N2200 is presented.Consistent descriptions with equal quality are obtained by using the extended Gaussian disorder model?EGDM?and the extended correlated disorder model?ECDM?,within which the mobility depends on the electric field and carrier density and within which spatial correlations between the site energies are absent or are included.Based on a comparison of the model parameters as obtained from both models,it is found that the more realistic intersite distance found using the EGDM?0.8 nm?compared to the value found using the ECDM?0.1nm?as an indication that in N2200 correlations between the site energies are absent or play a minor role.Finally,electron-only devices with Ohmic contacts are demonstrated,exhibiting trap-free space-charge-limited currents.While the high room-temperature mobility of 5×10^-8m²/Vsfor electrons are determined.The presence of spatial correlation between the disorder transport site energies in semiconducting polymers used in organic electronic devices is known to affect the mobility.However,it is not established whether such a correlation is present in relevant polymers.The thickness dependent and temperature dependent J-V characteristics of N2200 electron-only devices can be accurately described by using EGDM and ECDM,respectively.Both models contain a carrier density dependence of mobility.But with the EGDM?2.0nm?a more realistic value of the intersite distance is found than in the case of the ECDM?0.4 nm?.This is an indication that site-energy correlations do not play an important role in N2200.