A record high OFET hole mobility, as high as 23.7 cm(2) /Vs, is achieved in macroscopic aligned semiconducting polymers. The high mobility is insensitive to the polymer molecular weight. Polymer chains are aligned along the fiber to facilitate intrachain charge transport.

The development of organic semiconductors for use in thermoelectrics requires the optimization of both their thermopower and electrical conductivity. Here two fundamentally different doping mechanisms are used to investigate the thermoelectric properties of known high hole mobility polymers: poly 3‐hexylthiophene (P3HT), poly(2,5‐bis(3‐tetradecylthiophen‐2‐yl)thieno[3,2‐b]thiophene) (PBTTT‐C14), and poly(2,5‐bis(thiphen‐2‐yl)‐(3,7‐diheptadecantyltetrathienoacene)) (P2TDC17‐FT4). The small molecule tetrafluorotetracyanoquinodimethane (F4TCNQ) is known to effectively dope these polymers, and the thermoelectric properties are studied as a function of the ratio of dopant to polymer repeat unit. Higher electrical conductivity and values of the thermoelectric power factor are achieved by doping with vapor‐deposited fluoroalkyl trichlorosilanes. The combination of these data reveals a striking relationship between thermopower and conductivity in thiophene‐based polymers over a large range of electrical conductivity that is independent of the means of electrical doping. This relationship is not predicted by commonly used transport models for semiconducting polymers and is demonstrated to hold for other semiconducting polymers as well.

Solution processable semiconducting polymers with excellent film forming capacity and mechanical flexibility are considered among the most progressive alternatives to conventional inorganic semiconductors. However, the random packing of polymer chains and the disorder of the polymer matrix typically result in low charge transport mobilities (10(-5)-10(-2) cm(2) V(-1) s(-1)). These low mobilities compromise their performance and development. Here, we present a strategy, by utilizing capillary action, to mediate polymer chain self-assembly and unidirectional alignment on nanogrooved substrates. We designed a sandwich tunnel system separated by functionalized glass spacers to induce capillary action for controlling the polymer nanostructure, crystallinity, and charge transport. Using capillary action, we demonstrate saturation mobilities with average values of 21.3 and 18.5 cm(2) V(-1 )s(-1) on two different semiconducting polymers at a transistor channel length of 80 μm. These values are limited by the source-drain contact resistance, Rc. Using a longer channel length of 140 μm where the contact resistance is less important, we measured μh = 36.3 cm(2) v(-1) s(-1). Extrapolating to infinite channel length where Rc is unimportant, the intrinsic mobility for poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']dithiophen-2-yl)-alt-[1,2,5]thiadiazolo[3,4-c]pyridine] (Mn = 140 kDa) at this degree of chain alignment and structural order is μh ≈ 47 cm(2 )v(-1) s(-1). Our results create a promising pathway toward high performance, solution processable, and low-cost organic electronics.

The orientational correlation length of domains in a semiconducting polymer controls its thermoelectric performance.

A new class of high-performance n-type organic thermoelectric materials, self-doping perylene diimide derivatives with modified side chains, is reported. These materials achieve the highest n-type thermoelectric performance of solution-processed organic materials reported to date, with power factors as high as 1.4 μW/mK(2). These results demonstrate that molecular design is a promising strategy for enhancing organic thermoelectric performance.