Two‐Dimensional Carrier Distribution in Top‐Gate Polymer Field‐Effect Transistors: Correlation between Width of Density of Localized States and Urbach Energy

Abstract

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.

Improved Heterojunction Quality in Cu₂O-based Solar Cells Through the Optimization of Atmospheric Pressure Spatial Atomic Layer Deposited <br />Zn_1-xMg_xO

“…To verify the presence of CuO on the surface of Cu 2 O, absorption spectra of the etched and unetched thermally oxidized Cu 2 O substrates were taken with photothermal deflection spectroscopy (PDS) -a highly sensitive technique which allows for sub-band gap absorption measurement 24 ( Figure 4). Both spectra showed absorption above 1.4 eV, which coincides with the band gap of CuO, before saturating at 2 eV (Cu 2 O band gap).…”

Investigation of the dimensionality of charge transport in organic field effect transistors

“…As mentioned earlier, in previously published numerical investigations of OFETs a Gaussian distribution was assumed for the DOS [12,13]. Although this assumption might be correct for ODSCs in general, it is not commonly used for analyzing experimental investigations of OFETs [14][15][16]19]. In fact we found that regardless of the value for the width of the DOS, a Gaussian distribution leads to a near-constant mobility over the whole field range and, in fact, slightly decreases with increasing gate field.…”

“…In the linear transport regime the exponents follow to γ 2D = T 0 /T and γ 3D = 2T 0 /T − 1, respectively, where T is the lattice temperature [15]. In the saturation regime the corresponding exponents follow to γ 2D = T 0 /T + 1 and γ 3D = 2T 0 /T for 2D and 3D transports, respectively [16]. The procedure to obtain the dimensionality of a system can, in short, be described as follows.…”

“…Selfassembled monolayer field effect transistors with a single ML of dimethylsilane and FETs with an evaporated single ML of T6-where the spatial extension of the conduction channel is intrinsically limited to one ML-were found to be 2D in the linear regime [15]. Interestingly, dimensionality investigations according to the eVM of FETs operating in the saturation regime with bulk spin-coated layers of various polymers with thicknesses ranging from 60 to 100 nm showed 2D transport for all systems [16]. It should be mentioned that in Refs.…”

“…It should be mentioned that in Refs. [15,16] the linear fits of the temperature dependence of γ were forced to fall on the best-matching integer value predicted by the eVM model.…”