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Two-dimensional carrier distribution in top-gate polymer field-effect transistors: correlation between width of density of localized states and Urbach energy.

Kronemeijer AJ, Pecunia V, Venkateshvaran D, Nikolka M, Sadhanala A, Moriarty J, Szumilo M, Sirringhaus H - Adv. Mater. Weinheim (2013)

Bottom Line: A general semiconductor-independent two-dimensional character of the carrier distribution in top-gate polymer field-effect transistors is revealed by analysing temperature-dependent transfer characteristics and the sub-bandgap absorption tails of the polymer semiconductors.A correlation between the extracted width of the density of states and the Urbach energy is presented, corroborating the 2D accumulation layer and demonstrating an intricate connection between optical measurements concerning disorder and charge transport in transistors.

View Article: PubMed Central - PubMed

Affiliation: Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.

No MeSH data available.


Related in: MedlinePlus

Visualisation of the parameter space that yields identical fits of the temperature-dependent transfer characteristics of PSeDPPDTT FETs using Equation (1). The resulting fits are shown as solid lines in Figure 1a. A threshold voltage Vt = +1 V was used. Dashed lines are a guide to the eye showing expected relationships between the parameters from Equation (1).
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fig06: Visualisation of the parameter space that yields identical fits of the temperature-dependent transfer characteristics of PSeDPPDTT FETs using Equation (1). The resulting fits are shown as solid lines in Figure 1a. A threshold voltage Vt = +1 V was used. Dashed lines are a guide to the eye showing expected relationships between the parameters from Equation (1).

Mentions: Returning to the 2D model, we would like to comment on the fitting of the complete transfer characteristics using the 2D model as shown in Figure a. With the T0 values for the different polymers determined from the aforementioned analysis, Equation (1) contains three additional parameters to describe the complete transfer characteristics of the FETs. The three parameters, i.e., α−1, dsc and σ0, are to be determined. We found, however, that there is no unambiguous set of values for these parameters that could be determined from the fit shown in Figure 1a. Over a wide range of values the parameters α−1 and dsc are interchangeable in order to match the temperature dependence of the charge transport, with the parameter σ0 available to adjust the absolute value of the source-drain current for a particular combination of α−1 and dsc. Figure6 illustrates the parameter space for which identical quality fits to the experimental data are obtained. Relationships between the parameters are observed that are in accordance with Equation (1). In the present case of top-gate FETs with relatively thick semiconductor layers it is not possible to fix dsc a priori, in contrast with the case of the SAMFET where the thickness of the semiconductor is known and set as the accumulation layer thickness. For (semi)crystalline polymer films with edge-on, lamellar orientation, such as P3HT or PBTTT, it is tempting to assume the thickness of the first layer of polymer chains in the unit cell to define the accumulation layer thickness dsc. We have therefore constrained the analysis to dsc ≤ 2 nm. In amorphous polymers or polymers with face-on orientation it is less clear, a priori, how to determine a unique value for dsc.


Two-dimensional carrier distribution in top-gate polymer field-effect transistors: correlation between width of density of localized states and Urbach energy.

Kronemeijer AJ, Pecunia V, Venkateshvaran D, Nikolka M, Sadhanala A, Moriarty J, Szumilo M, Sirringhaus H - Adv. Mater. Weinheim (2013)

Visualisation of the parameter space that yields identical fits of the temperature-dependent transfer characteristics of PSeDPPDTT FETs using Equation (1). The resulting fits are shown as solid lines in Figure 1a. A threshold voltage Vt = +1 V was used. Dashed lines are a guide to the eye showing expected relationships between the parameters from Equation (1).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230477&req=5

fig06: Visualisation of the parameter space that yields identical fits of the temperature-dependent transfer characteristics of PSeDPPDTT FETs using Equation (1). The resulting fits are shown as solid lines in Figure 1a. A threshold voltage Vt = +1 V was used. Dashed lines are a guide to the eye showing expected relationships between the parameters from Equation (1).
Mentions: Returning to the 2D model, we would like to comment on the fitting of the complete transfer characteristics using the 2D model as shown in Figure a. With the T0 values for the different polymers determined from the aforementioned analysis, Equation (1) contains three additional parameters to describe the complete transfer characteristics of the FETs. The three parameters, i.e., α−1, dsc and σ0, are to be determined. We found, however, that there is no unambiguous set of values for these parameters that could be determined from the fit shown in Figure 1a. Over a wide range of values the parameters α−1 and dsc are interchangeable in order to match the temperature dependence of the charge transport, with the parameter σ0 available to adjust the absolute value of the source-drain current for a particular combination of α−1 and dsc. Figure6 illustrates the parameter space for which identical quality fits to the experimental data are obtained. Relationships between the parameters are observed that are in accordance with Equation (1). In the present case of top-gate FETs with relatively thick semiconductor layers it is not possible to fix dsc a priori, in contrast with the case of the SAMFET where the thickness of the semiconductor is known and set as the accumulation layer thickness. For (semi)crystalline polymer films with edge-on, lamellar orientation, such as P3HT or PBTTT, it is tempting to assume the thickness of the first layer of polymer chains in the unit cell to define the accumulation layer thickness dsc. We have therefore constrained the analysis to dsc ≤ 2 nm. In amorphous polymers or polymers with face-on orientation it is less clear, a priori, how to determine a unique value for dsc.

Bottom Line: A general semiconductor-independent two-dimensional character of the carrier distribution in top-gate polymer field-effect transistors is revealed by analysing temperature-dependent transfer characteristics and the sub-bandgap absorption tails of the polymer semiconductors.A correlation between the extracted width of the density of states and the Urbach energy is presented, corroborating the 2D accumulation layer and demonstrating an intricate connection between optical measurements concerning disorder and charge transport in transistors.

View Article: PubMed Central - PubMed

Affiliation: Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge, CB3 0HE, United Kingdom.

No MeSH data available.


Related in: MedlinePlus