# Electrospun Nanofibers for Integrated Sensing, Storage, and Computing Applications
## 3 Electrospun Nanofibers in Transistors: Computation and Multifunctional Electronics
### Nanofiber Materials and Transistor Performance  
There is no denying that the conductive polymer is the earliest material introduced to the channel layer for the classic transistor in the early stages of the development of the electrospinning technique. As early as 2003, cambrosulfonic-acid-doped PEO prepared by electrospinning was creatively used as the semiconductor layer instead of the common use for the substrate [61]. Corresponding FET was demonstrated to have the typical I-V characteristics and its mobility was measured to be 1.43 \(\times\) 10\({}^{-4}\) cm\({}^{2}\) V\({}^{-1}\) s\({}^{-1}\). Since then, more and more organic polymers were brought to this new field. P3 HT is one of the most widely used polymers in the organic thin-film transistor (OTFT) and displays new vigor when transformed into nanofiber by electrospinning. The mobility of transistors with a P3 HT active layer has been increased from 4 \(\times\) 10\({}^{-4}\) to 2 in recent years, experiencing several orders of magnitude of improvement [62; 63; 64]. The main reason for the unsatisfactory mobility of the polymer organic field-effect transistor (OFET) is the molecular \begin{table}
\begin{tabular}{c c c} \hline \hline
**Category** & **Detailed Factors** & **Changes in Nanofibers** \\ \hline \multirow{6}{*}{Solution Variables} & Target material concentration & Fiber diameter increases with \\  & the rising concentration \\ \cline{2-3}  & Electrical conductivity of the solution & Fiber diameter increases with the rising conductivity. \\ \cline{2-3}  & Viscosity and surface tension of the solution & Too high or too low factors lead to \\  & & poor fiber morphology. \\ \cline{2-3}  & The molecular weight of the target material & Fiber diameter decreases with increasing \\  & & molecular weight. \\ \hline \multirow{3}{*}{Conditions of Electrosppinning Process} & Spinneret inner diameter & Fiber size is smaller with a smaller \\  & Spinneret inner diameter. \\ \cline{2-3}  & Flow rate & High flow rate causes increased fiber diameter. \\ \cline{2-3}  & Distance between the needle and the collector & Smaller distance results in larger fiber diameter. \\ \hline \multirow{2}{*}{Environmental Factors} & Ambient humidity & High humidity prolongs the produced jet. \\ \cline{2-3}  & surrounding temperature & Temperature controls the viscosity of the solution \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Parameters influencing the nanofibers’ characteristics in the electrospinning process. self-organization and structural defects that provide trapping or scattering sites. Later, a high-performance polymer, OFET, based on PANI nanofibers was put forward with super-high charge mobility of 11.6 cm\({}^{2}\) V\({}^{-1}\) s\({}^{-1}\), for the reason that the quasi-1D nanostructure of electrospun fibers promoted the charge transfer by reducing grain boundary and doped gold nanoparticles provide \"conducting bridges\" between the semiconducting domains of PANI [65]. Moreover, combined with its portable nature, polymer FET exhibited high bending stability and flexibility. Aligned organic nanofibers composed of PEO, which assisted in the processing and semiconducting polymer PQT-12 of semiconducting properties, were spread on the stretchable poly(dimethylsiloxane) (PDMS)/poly(ethylene terephthalate) (PET) composite substrate to fabricate flexible FET, shown in Figure 9a, and these transistors showed remarkably higher mechanical stability than the ones deposited on the PDMS-only or film-type PET substrates [66]. Under strict bending conditions with a bending radius of 0.75 mm and repeated tests over 1000 cycles, its on-current retention could reach 82.3 (\(\pm\)6.7)%, while retention could hold to be 32.6 (\(\pm\)11.4)% and 14.6 (\(\pm\)20.0)% for transistors on PET and PDMS substrates, respectively (Figure 9b,c). Besides the application of organic FET, metal oxide semiconducting nanofibers produced by electrospinning technology open up new possibilities for the fabrication of the field-effect transistor.