25th Anniversary Article: Organic Field‐Effect Transistors: The Path Beyond Amorphous Silicon

Abstract

Over the past 25 years, organic field-effect transistors (OFETs) have witnessed impressive improvements in materials performance by 3–4 orders of magnitude, and many of the key materials discoveries have been published in Advanced Materials. This includes some of the most recent demonstrations of organic field-effect transistors with performance that clearly exceeds that of benchmark amorphous silicon-based devices. In this article, state-of-the-art in OFETs are reviewed in light of requirements for demanding future applications, in particular active-matrix addressing for flexible organic light-emitting diode (OLED) displays. An overview is provided over both small molecule and conjugated polymer materials for which field-effect mobilities exceeding > 1 cm2 V–1 s–1 have been reported. Current understanding is also reviewed of their charge transport physics that allows reaching such unexpectedly high mobilities in these weakly van der Waals bonded and structurally comparatively disordered materials with a view towards understanding the potential for further improvement in performance in the future.

Diketopyrrolopyrrole‐Based Conjugated Polymer Entailing Triethylene Glycols as Side Chains with High Thin‐Film Charge Mobility without Post‐Treatments

“…Moreover, a scattering signal at q y = 17.4 nm −1 in the in‐plane direction emerges for thin film of PDPP3T‐1, which is attributed to the interchain π−π stacking with a distance of 0.361 nm. These GIWAXS data indicate that polymer chains of PDPP3T‐1 are predominantly packed in edge‐on mode on the OTS ( n ‐octadecyltrichlorosilane) modified SiO 2 /Si substrate, which is believed to be favorable for charge transport 2, 16. It is noted that the GIWAXS pattern of PDPP3T‐1 is almost unchanged aside from a slight enhancement in scattering intensities after thermal annealing at 100 °C, in good agreement with the observation that thin‐film hole mobility remains almost unchanged following thermal annealing.…”

Small Molecule/Polymer Blend Organic Transistors with Hole Mobility Exceeding 13 cm2 V−1 s−1

“…Photoemission measurements were performed by scanning the wavelength of incident light between 6.2 and 4.4 eV and monitoring the photocurrent response. The HOMO level was then extracted using Fowler analysis, by plotting the cube-root of the photocurrent signal and extrapolation to the zero baseline [1]. All measurements were carried out in ambient atmosphere at room temperature and approx.…”

“…[1] [2] The desire for roll-to-roll printed, transparent, flexible electronics with greater economic viability has driven extensive research in the field, leading to substantial advances in the electronic properties of organic materials. These developments are illustrated by the overall rise in charge carrier mobilities -a crucial figure of merit -in organic thin-film transistors (OTFTs).…”

“…These developments are illustrated by the overall rise in charge carrier mobilities -a crucial figure of merit -in organic thin-film transistors (OTFTs). [1] [3] [4] Over the past few years, this evolution has not only allowed organics to outperform dominant inorganic technologies such as amorphous silicon (aSi), but it has excelled to the point that solution-processed organic transistors have now surpassed the benchmark mobility of 10 cm 2 /Vs, moving OTFTs into the realm of industrial applications. [5] [6] [7] [8] [9] [10] [11] [12] Organic semiconducting blends consisting of a small molecule and a polymerrenowned for their complexity as well as their advantageous electronic qualities -provide one of the most auspicious systems for realising the application of OTFTs in future electronic technologies.…”

A Facile Approach to Improve Interchain Packing Order and Charge Mobilities by Self‐Assembly of Conjugated Polymers on Water

“…The past decades have witnessed the significant progresses in the development of organic and polymeric semiconductors with high charge mobilities 1, 2, 3, 4. Various conjugated molecules and polymers have been investigated intensively 5, 6, 7, 8, 9, 10, 11.…”