Polyferrocenylsilane Semicrystalline Polymer Additive for Solution-Processed p-Channel Organic Thin Film Transistors

Zhengran He,Sheng Bi,Jihua Chen,Ziyang Zhang,Kyeiwaa Asare-Yeboah,Dawen Li

doi:10.3390/polym13030402

Abstract

In this study, we demonstrated for the first time that a metal-containing semicrystalline polymer was used as an additive to mediate the thin film morphology of solution-grown, small-molecule organic semiconductors. By mixing polyferrocenylsilane (PFS) with an extensively-studied organic semiconductor 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS pentacene), PFS as a semicrystalline polymer independently forms nucleation and crystallization while simultaneously ameliorating diffusivity of the blend system and tuning the surface energies as a result of its partially amorphous property. We discovered that the resultant blend film exhibited a 6-fold reduction in crystal misorientation angle and a 3-fold enlargement in average grain width. Enhanced crystal orientation considerably reduces mobility variation, while minimized defects and trap centers located at grain boundaries lessen the adverse impact on the charge transport. Consequently, bottom-gate, top-contact organic thin film transistors (OTFTs) based on the TIPS pentacene/PFS mixture yielded a 40% increase in performance consistency (represented by the ratio of average mobility to the standard deviation of mobility). The PFS semicrystalline polymer-controlled crystallization can be used to regulate the thin film morphology of other high-performance organic semiconductors and shed light on applications in organic electronic devices.

Highlights

Polymeric materials as additives have rapidly attracted considerable attention for application in organic electronics [1,2,3,4,5]. When they are blended with organic semiconductors, those polymers demonstrate various merits in controlling the crystal growth, enhancing the semiconductor morphology, and improving the electrical performance of organic thin film transistors (OTFTs) [6,7]
We demonstrated for the first time the utilization of a metal-containing polymer-polyferrocenylsilane (PFS) semicrystalline polymer to control the crystal alignment, film morphology, and charge transport of solution-processed, small-molecular organic semiconductors
Bottom-gate, top-contact OTFTs were fabricated by using the TIPS pentacene/PFS blends as an active layer, which demonstrates a 40% increase in device electrical performance consistency

Summary

Introductions

Polymeric materials as additives have rapidly attracted considerable attention for application in organic electronics [1,2,3,4,5] When they are blended with organic semiconductors, those polymers demonstrate various merits in controlling the crystal growth, enhancing the semiconductor morphology, and improving the electrical performance of organic thin film transistors (OTFTs) [6,7]. At an optimized sweeping speed of 0.75–2.0 mm/s and an elevated temperature, reduced interfacial trap density and improved OTFT performance were both observed Despite these advances, the complexity of experimental setup and precise parameter control of these external alignment methods may be rather challenging or even undesirable in all kinds of organic electronics applications [29]. Bottom-gate, top-contact OTFTs were fabricated by using the TIPS pentacene/PFS blends as an active layer, which demonstrates a 40% increase in device electrical performance consistency

Experiment

Results and Discussion

Polarized

Conclusions