Electric field activated nonlinear and disorder-induced charge transport in doped polymer devices (original) (raw)
Related papers
Modelling of the charge carrier mobility in disordered linear polymer materials
Physical chemistry chemical physics : PCCP, 2017
We introduced a molecular-scale description of disordered on-chain charge carrier states into a theoretical model of the charge carrier transport in polymer semiconductors. The presented model combines the quantum mechanical approach with a semi-classical solution of the inter-chain charge hopping. Our model takes into account the significant local anisotropy of the charge carrier mobility present in linear conjugated polymers. Contrary to the models based on the effective medium approximation, our approach allowed avoiding artefacts in the calculated concentration dependence of the mobility originated in its problematic configurational averaging. Monte Carlo numerical calculations show that, depending on the degree of the energetic and structural disorder, the charge carrier mobility increases significantly with increasing charge concentration due to trap filling. At high charge carrier concentrations, the effect of the energetic disorder disappears and the mobility decreases sligh...
Journal of Physics D: Applied Physics, 2014
Electric field activated charge transport is studied in the metal/polymer/metal device structure of electropolymerized polypyrrole down to 10 K with varying carrier density and disorder. Disorder induced nonlinear behaviour is observed in polypyrrole devices grown at room temperature which is correlated to delocalization of states. The slope parameter of currentvoltage characteristics (in log-log scale) increases as the temperature decreases, which indicates the onset of stronger field dependence. The field dependence of mobility becomes dominant as the carrier density decreases. The sharp dip in differential conductance indicates the localization of carriers at low temperatures which reduces the effective number of carriers involved in the transport.
Polymer electronic materials: a review of charge transport
Polymer International, 2006
This article presents an overview of the charge transport phenomenon in semiconducting polymer materials. In these disordered systems both intrinsic and extrinsic parameters play significant roles. In general, π-electron delocalization, interchain interaction, band gap, carrier density, extent of disorder, morphology and processing of materials determine the electrical and optical properties. The chemical structure, especially the role of side groups, is quite important in both physical and processing properties. The nature of charge carriers and their role in charge transport depend on the structure and morphology of the system. Hence in several semiconducting polymer devices, the correlations among structure, morphology and transport are rather strong. The dependence of carrier mobility on temperature and electric field needs to be understood in the framework of competing models based on carrier hopping, trapping/detrapping and tunneling. Exactly what determines the dispersive/nondispersive, polaronic and correlative transport regimes is yet to be quantified. An understanding of the carrier mobility in semiconducting polymers is necessary to optimize the performance of polymeric electronic devices.
First-principles determination of charge carrier mobility in disordered semiconducting polymers
Physical Review B, 2010
We propose a theoretical method that can predict carrier mobility in disordered semiconducting polymers and organic semiconductors from first principles. The method is based on nonadiabatic ab initio molecular dynamics and static master equation, treating dynamic and static disorder on the same footing. We have applied the method to calculate the hole mobility in disordered poly͑3-hexylthiophene͒ conjugated polymers as a function of temperature and electric field and obtained excellent agreements with corresponding experimental results. The method could be used to explore structure-mobility relation in disordered semiconducting polymers/organic semiconductors and aid rational design of these materials.
Charge-carrier transport in disordered polymers
Journal of Polymer Science Part B: Polymer Physics, 2003
General properties of charge carrier transport in disordered organic materials are discussed. Spatial correlation between energies of transport sites determines the form of the drift mobility field dependence. Particular kind of spatial correlation in a disordered material depends on its nature. Mobility field dependences have to be different in polar and nonpolar materials. Different methods of mobility calculation from the shape of photocurrent transient are analyzed. A widely used method is very sensitive to the variation of the shape of the transient and sometimes produces results that effectively masquerade the true dependence of the mobility on electric field or trap concentration. Arguments in favor of the better, more reliable method are suggested. Charge transport in materials containing charged traps is considered without using the isolated trap approximation and this leads to qualitatively different results. They indicate that the effect of charged traps can hardly be responsible for experimentally observed transport properties of disordered organic materials.
Polymers for Advanced Technologies, 2009
The theoretical model of the inter-chain charge carrier mobility in poly[2-methoxy-5-(2(-ethylhexyloxy)-p-phenylene vinylene] (MEH-PPV) doped with polar additive is put forward. The polymer chain states of a charge carrier were calculated by means of diagonalization of a tight-binding Hamiltonian, which includes disorder in both the local energies and transfer integrals. Consequently, the inter-chain charge carrier transport is taking place on a spatially and energetically disordered medium. Because it is believed that the additive does not significantly influence the polymer supramolecular structure, the polymer conformations were simplified as much as possible. On the other hand, the energetic disorder is rigorously described. The transfer rates between the polymer chains were determined using the quasi-classical Marcus theory. The model considered the following steps of the charge carrier transport: the charge carrier hops to a given polymer chain. Then, the charge carrier thermalizes to the Boltzmann distribution over all its possible states on this chain. After that, the charge carrier hops to any possible state on one of the four nearest neighboring chains. The results showed that the inter-chain charge carrier mobility is very strongly dependent on the degree of the energetic disorder. If the energetic disorder is doubled from 0.09 to 0.18 eV, the mobility decreases by two or three orders of magnitude.
Nonlinear transport in semiconducting polymers at high carrier densities
Nature Materials, 2009
Conducting and semiconducting polymers are important materials in the development of printed, flexible, large-area electronics such as flat-panel displays and photovoltaic cells. There has been rapid progress in developing conjugated polymers with high transport mobility required for high-performance field-effect transistors (FETs), beginning 1 with mobilities around 10 −4 cm 2 V −1 s −1 to a recent report 2 of 1 cm 2 V −1 s −1 for poly(2,5-bis(3-tetradecylthiophen-2yl)thieno[3,2-b]thiophene) (PBTTT). Here, the electrical properties of PBTTT are studied at high charge densities both as the semiconductor layer in FETs and in electrochemically doped films to determine the transport mechanism. We show that data obtained using a wide range of parameters (temperature, gate-induced carrier density, source-drain voltage and doping level) scale onto the universal curve predicted for transport in the Luttinger liquid description of the one-dimensional 'metal'.
Disorder in Charge Transport in doped polymers
Advanced Materials, 1994
moved to his present position in 1970. His research interests include electro-optic properties of organic solids. 200 I VCH ~,rla~Fjiepell~~hrrfr nihH 0.69469 Wetnhetm I Y Y 4 0935-9648/9410303-0200 $ 5 OO+ 2510 Ad1 Maler 1994, 6. No 3 202 ( C CIl Verlug~~e.wlldtaft mhli 0-69469 Weinham 1994 o935-964si94lO303-o2O2 R 5 00+ 25'0 Adv Muter 1994, 6, No 1