Improving Charge Mobility of Polymer Transistors by Judicious Choice of the Molecular Weight of Insulating Polymer Additive

Abstract

In this work, we have carefully examined the morphology of semiconducting polymer:insulating polymer blends, which were deposited from inkjet printing. We attempted to study the impact of molecular weight (MW) of insulating polymer on the nanoscale morphology and function of the blends. The morphology of all of the inkjet-printed samples was characterized by small-angle neutron scattering (SANS), grazing incidence X-ray diffraction (GIXD), and atomic force microscopy (AFM). The SANS results show that the domain size of the blends increases by increasing the MW of insulating polymer, while the domain purity reaches the maximum with proper molecular weight of insulating polymer. AFM images show that the connectivity of semiconducting polymer domains is disrupted with addition of polystyrene (PS) with low molecular weight (M w = 2.5K and 20K), while well-interconnected domains are observed with addition of PS with high molecular weight (M w = 182K and 2000K). GIXD results indicate that the π–π stacking distance of semiconducting polymer can be shortened with addition of PS and decreases with an increase of PS molecular weight from 2.5K to 182K. Further increasing molecular weight of PS to 2000K results in very weak π–π stacking ordering. This work demonstrates that the domain purity, connectivity of semiconducting polymer domains, and molecular packing are crucial for the charge transport. The judicious choice of the MW of insulating polymer could carefully control the nanoscale morphology of semiconducting polymer:insulating polymer blends, which could provide blend morphology with high domain purity, well-connected domains, along with reduced π–π stacking distance, all of which facilitate charge transport, resulting in a significant improvement of charge mobility.

Converging the Hole Mobility of Poly(2-N-carbazoylethyl acrylate) with Conjugated Polymers by Tuning Isotacticity

“…Sample 4a was somewhat of an outlier in this regard as it showed the highest mobility out of 4a−4e after annealing, likely due to the higher molecular weight of the polymer. 46 However, for the highly isotactic polymers 4f−4i, the mobilities increased more drastically and fully consistent with the trend in tacticity. Specifically, polymer 4i (m = 94.7%) saw an increase from 4.68 × 10 −5 cm 2 V −1 s −1 to 2.74 × 10 −4 cm 2 V −1 s −1 , which is comparable to hole mobility of the wellknown conjugated polymer poly(3-hexylthiophene) (P3HT), as seen in Table 1.…”

“…Polymers 4a – 4e ( m = 45.5–65.8%) saw a relatively small increase in hole mobility with annealing. Sample 4a was somewhat of an outlier in this regard as it showed the highest mobility out of 4a – 4e after annealing, likely due to the higher molecular weight of the polymer . However, for the highly isotactic polymers 4f – 4i , the mobilities increased more drastically and fully consistent with the trend in tacticity.…”

High Performance Flexible Nonvolatile Memory Based on Vertical Organic Thin Film Transistor

“…High molecular weight π‐extended organic p‐type semiconductor copolymer poly[2,5‐bis(alkyl)pyrrolo[3,4‐c]pyrrole‐1,4(2H,5H)‐dione‐alt‐5,5′‐ di(thiophen‐2‐yl)‐2,2′‐(E)‐2‐(2‐(thiophen‐2‐yl)vinyl)‐thiophene] (PDVT‐8) ( M w = 50 K, polymer dispersity index (PDI) = 2.4) was obtained from 1‐Materials, which was dissolved in chloroform (10 mg mL −1 ) . Poly(4‐vinylphenol) (PVP) ( M w = 25 000), 4,4′‐(hexafluoroisopropylidene)‐diphthalic anhydride (HDA) (99%), and propylene glycol monomethyl ether acetate (PGMEA) (≥99.5%) were obtained from Sigma‐Aldrich.…”

Impact of Fullerene Structure on Nanoscale Morphology and Miscibility and Correlation of Performance on Small Molecules: Fullerene Solar Cell

“…To verify the connectivity of domains, the SANS curves were also fitted to the Teubner–Strey (TS) model . This model is commonly used to describe the bicontinuous two-phase systems. − The TS model is given by where I b is the incoherent scattering, a 2 , c 1 , and c 2 are associated with correlation length (ξ TS ) and the repeating distance of two adjacent domains ( d ): ξ TS is related to average domain size of the fullerene phase and the p-DTS­(FBTTh 2 ) 2 -rich phase. d is related to the length scale of the p-DTS­(FBTTh 2 ) 2 -rich phase.…”