Conjugated polymer chains have many degrees of conformational freedom and interact weakly with each other, resulting in complex microstructures in the solid state. Understanding charge transport in such systems, which have amorphous and ordered phases exhibiting varying degrees of order, has proved difficult owing to the contribution of electronic processes at various length scales. The growing technological appeal of these semiconductors makes such fundamental knowledge extremely important for materials and process design. We propose a unified model of how charge carriers travel in conjugated polymer films. We show that in high-molecular-weight semiconducting polymers the limiting charge transport step is trapping caused by lattice disorder, and that short-range intermolecular aggregation is sufficient for efficient long-range charge transport. This generalization explains the seemingly contradicting high performance of recently reported, poorly ordered polymers and suggests molecular design strategies to further improve the performance of future generations of organic electronic materials.

http://absimage.aps.org/image/MAR14/MWS_MAR14-2013-020288.pdf

A general relationship between disorder, aggregation and charge transport in conjugated polymers

In this review, we provide an overview of conjugated organic semiconductors and their applications in biological sensing with a primary focus on the role of the organic semiconductor. We cover work carried out with polymers as well as small molecules, from the well-established and commercially available systems to the emerging and recently developed materials.

/pdf/organic-semiconductors-for-biological-sensing-4a5br4evzr.pdf

Organic semiconductors for biological sensing

Recent Advances in the Bias Stress Stability of Organic Transistors

Formation of the semiconductor/dielectric double-layered films via vertical phase separations from polymer blends is an effective method to fabricate organic thin-film transistors (OTFTs). Here, we introduce a simple one-step processing method for the vertical phase separation of poly(3-hexylthiophene-2,5-diyl) (P3HT) and poly(methyl methacrylate) (PMMA) blends in OTFTs and their applications for high-performance nitrogen dioxide (NO2) sensors. Compared to the conventional two-step coated OTFT sensors, one-step processed devices exhibit a great enhancement of the responsivity from 116 to 1481% for 30 ppm NO2 concentration and a limit of detection of ∼0.7 ppb. Studies of the microstructures of the blend films and the electrical properties of the sensors reveal that the devices formed by the one-step vertical phase separation have better capability for the adsorption of NO2 molecules. Moreover, a careful adjustment of the blend ratio between P3HT and PMMA can further improve the performance of the NO2 sensors, ranging from sensitivity to selectivity and to the ability of recovery. This simple one-step processing method demonstrates a potential possibility for developing high-performance, low-cost, and large-area OTFT gas sensors.

Phase Separation of P3HT/PMMA Blend Film for Forming Semiconducting and Dielectric Layers in Organic Thin-Film Transistors for High-Sensitivity NO2 Detection.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/adfm.202105456

Organic Semiconductor/Insulator Blends for Elastic Field-Effect Transistors and Sensors

Ultrathin semiconductor films for NH3 gas sensors prepared by vertical phase separation

One-pot synthesized ABA tri-block copolymers for high-performance organic field-effect transistors

Polymer semiconductors with high crystallinity and high molecular orientation have been demonstrated to be in favor of improving the bias-stress stability of organic field-effect transistors (OFETs). The isoindigo (IID)-bithiophene (BT) based conjugated polymer (PIID-BT) is a typical donor–acceptor polymer with higher hole mobility and can be used for the bias-stress stability study. In this work, we use a small organic molecule of FePc to optimize the morphology and structure of the PIID-BT semiconductor to improve the bias-stress stability of OFET devices. The high crystallinity and ordered morphology of the FePc-doped PIID-BT film are realized, and this as-obtained FePc-doped PIID-BT OFET shows more outstanding bias-stress stability, with a lower drain current decay of only 12% over a stressing time of 1000 s than that of ca. 50% for the pristine PIID-BT devices. The electronic structure features reveal the bind between FePc and PIID-BT molecules via the Fe-O coordination interaction, which would be responsible for the efficiently oriented growth of the PIID-BT polymer and eventually promote the bias-stress stability of PIID-BT based OFET devices.Polymer semiconductors with high crystallinity and high molecular orientation have been demonstrated to be in favor of improving the bias-stress stability of organic field-effect transistors (OFETs). The isoindigo (IID)-bithiophene (BT) based conjugated polymer (PIID-BT) is a typical donor–acceptor polymer with higher hole mobility and can be used for the bias-stress stability study. In this work, we use a small organic molecule of FePc to optimize the morphology and structure of the PIID-BT semiconductor to improve the bias-stress stability of OFET devices. The high crystallinity and ordered morphology of the FePc-doped PIID-BT film are realized, and this as-obtained FePc-doped PIID-BT OFET shows more outstanding bias-stress stability, with a lower drain current decay of only 12% over a stressing time of 1000 s than that of ca. 50% for the pristine PIID-BT devices. The electronic structure features reveal the bind between FePc and PIID-BT molecules via the Fe-O coordination interaction, which would be re...

Lingyun Liu

Papers

Ultrathin semiconductor films for NH3 gas sensors prepared by vertical phase separation

One-pot synthesized ABA tri-block copolymers for high-performance organic field-effect transistors

FePc induced highly oriented PIID-BT conjugated polymer semiconductor with high bias-stress stability