Microstructural control suppresses thermal activation of electron transport at room temperature in polymer transistors

Abstract

Recent demonstrations of inverted thermal activation of charge mobility in polymer field-effect transistors have excited the interest in transport regimes not limited by thermal barriers. However, rationalization of the limiting factors to access such regimes is still lacking. An improved understanding in this area is critical for development of new materials, establishing processing guidelines, and broadening of the range of applications. Here we show that precise processing of a diketopyrrolopyrrole-tetrafluorobenzene-based electron transporting copolymer results in single crystal-like and voltage-independent mobility with vanishing activation energy above 280 K. Key factors are uniaxial chain alignment and thermal annealing at temperatures within the melting endotherm of films. Experimental and computational evidences converge toward a picture of electrons being delocalized within crystalline domains of increased size. Residual energy barriers introduced by disordered regions are bypassed in the direction of molecular alignment by a more efficient interconnection of the ordered domains following the annealing process.

Understanding Charge Transport in High‐Mobility p‐Doped Multicomponent Blend Organic Transistors

“…We first measured the CMS spectra of the individual materials and their blends ( Figure 3b). C 16 IDT-BT-only devices show spectra with features typically observed for other semiconducting polymers: [27,29,30] a positive signal related to the bleaching of the semiconductor neutral absorption, with a maximum at 1.82 eV, and a broad negative signal related to charge absorption, in agreement with ΔT/T spectra measured by charge accumulation spectroscopy (CAS). [15] The bleaching measured with CMS matches the UV-vis absorption band of the neutral polymer ( Figure S5, Supporting Information), but with better-resolved features.…”

The Path to 20% Power Conversion Efficiencies in Nonfullerene Acceptor Organic Solar Cells

“…In addition, NMR techniques conducted in both in situ and ex situ conditions have been used to understand the phase transitions, crystallization, melting, and solid-to-solution transformations. [73,[74][75][76] Previously, a combination of X-ray scattering, ssNMR spectroscopy, and computational modeling techniques have been used to characterize the structures of π-conjugated systems [68,70] and D:A interactions in polymer:fullerene BHJ blends. [65] By analyzing and comparing the structural information gained from 1D and 2D NMR spectroscopy techniques, valuable information about the D:A inter-and intra-molecular interactions can be obtained.…”

Printable Organic‐Inorganic Nanoscale Multilayer Gate Dielectrics for Thin‐Film Transistors Enabled by a Polymeric Organic Interlayer

“…Thin-film transistors (TFTs) are traditional components of active matrix display backplanes and are envisioned for producing other types of circuitry for sensor and RFID applications. [1][2][3][4][5] A typical TFT consists of a gate electrode, a dielectric layer, a channel layer (n-or p-type semiconductor) and source/drain electrodes, where the most critical materials are the dielectric and the semiconductor since charge transport occurs in the channel layer in close proximity to the semiconductor-dielectric interface. [1] The past two decades have witnessed significant progress in developing solution-processable organic/inorganic semiconductor-based TFTs driven by the possibility of high throughput printing them at low costs, at low temperatures, and having compatibility with mechanically flexible substrates.…”