Highly Crystalline C8‐BTBT Thin‐Film Transistors by Lateral Homo‐Epitaxial Growth on Printed Templates

Abstract

Highly crystalline thin films of organic semiconductors offer great potential for fundamental material studies as well as for realizing high-performance, low-cost flexible electronics. The fabrication of these films directly on inert substrates is typically done by meniscus-guided coating techniques. The resulting layers show morphological defects that hinder charge transport and induce large device-to-device variability. Here, a double-step method for organic semiconductor layers combining a solution-processed templating layer and a lateral homo-epitaxial growth by a thermal evaporation step is reported. The epitaxial regrowth repairs most of the morphological defects inherent to meniscus-guided coatings. The resulting film is highly crystalline and features a mobility increased by a factor of three and a relative spread in device characteristics improved by almost half an order of magnitude. This method is easily adaptable to other coating techniques and offers a route toward the fabrication of high-performance, large-area electronics based on highly crystalline thin films of organic semiconductors.

High‐Mobility, Solution‐Processed Organic Field‐Effect Transistors from C8‐BTBT:Polystyrene Blends

“…[4] Therefore, in order to assess the intrinsic mobility in films that use our optimized morphology, we additionally discuss devices with gold electrodes. [4] Therefore, in order to assess the intrinsic mobility in films that use our optimized morphology, we additionally discuss devices with gold electrodes.…”

“…In the study that focused on the application of a UV-ozone treatment for the enhancement of the dielectric-semiconductor interface, effective mobilities as high as 6.5 cm 2 V −1 s −1 were achieved. [4] In the latter publication, the authors address the currently widely discussed issue of mobility overestimation. [24] Moreover, peak values of 9.1 cm 2 V −1 s −1 were reported for the same blend after recrystallization via solvent-vapor-annealing (SVA).…”

“…In particular, a mobility of 9.2 cm 2 V −1 s −1 has been extracted from blade-cast devices, prepared by a similar technology as utilized in our work. [4,25,29,30] Nonetheless, the current state-of-the-art solution deposition methods that report device performances for C8-BTBT often use silver (Ag) contacts [5,14,21,26,27] and do show gatevoltage-dependent mobilities. Without this correction, the actual effective mobility is between 6 and 7.4 cm 2 V −1 s −1 .…”

“…[3][4][5][6][7][8] Though these results are promising, some of these reported values suffer from overestimation, [9,10] require significant engineering efforts, [3] complex fabrication procedures, [4] or employ nonscalable fabrication techniques, [5] ultimately highlighting the need for alternative and potentially more industry-relevant processing methods. [3][4][5][6][7][8] Though these results are promising, some of these reported values suffer from overestimation, [9,10] require significant engineering efforts, [3] complex fabrication procedures, [4] or employ nonscalable fabrication techniques, [5] ultimately highlighting the need for alternative and potentially more industry-relevant processing methods.…”

Influence of the Surface Treatment on the Solution Coating of Single‐Crystalline Organic Thin‐Films

“…[6] To ensure good electrical characteristics, [43,44] the samples were annealed in a N 2 -filled glove box at a temperature of 50 °C for 10 h. Electrical characterizations were done using an Agilent Agt1500 in dry air. The transistor channel length and width was 190 and 2035 μm, respectively and the channel length was aligned with the casting direction so that the zone-cast ribbons tend to form bridges between the source and drain contacts.…”