Charge transport in high-performance ink-jet printed single-droplet organic transistors based on a silylethynyl substituted pentacene/insulating polymer blend

Abstract

We present a systematic study of the influence of material composition and ink-jet processing conditions on the charge transport in bottom-gate field-effect transistors based on blends of 6,13-bis(triisopropyl-silylethynyl) pentacene (TIPS-PEN) and polystyrene. After careful process optimizations of blending ratio and printing temperature we routinely can make transistors with an average mobility of 1 cm 2 /Vs (maximum value 1.5 cm 2 /Vs), on/off ratio exceeding 10 7 , and sharp turn-on in current (sub-threshold slopes approaching 60 mV/decade). These characteristics are superior to the TIPS-PEN only transistors. Using channel scaling measurements and scanning Kelvin probe microscopy, the sharp turn-on in current in the blends is attributed to a contact resistance that originates from a thin insulating layer between the injecting contacts and the semiconductor channel.

Large-area formation of self-aligned crystalline domains of organic semiconductors on transistor channels using CONNECT

“…S7). In comparison, other patterning methods used to create patterned OSCs for isolated OTFTs have shown relative variances ranging from 20% to 84% (9,15,17,22,31,32,35,42,(48)(49)(50)(51)(52)(53)(54). For example, Li et al (15) have shown that using a PMMA:C8BTBT blend on a solution wetting pattern can deposit crystal plates that have a mobility relative variance of >40%.…”

“…For instance, alignment using inkjet printing is restricted by the registration capability of the instrument, whereas the size of each OTFT is limited by the droplet size attainable (22,31). Another potential issue with these methods is the variance in electrical characteristics of TFTs due to the difficulty in obtaining uniform crystal growth on isolated TFTs over large areas (9,15,21,27,28,(31)(32)(33)(34)(35). Even single crystalline domains of patterned TFTs may have large variability in electrical characteristics as a result of random orientation and size variance.…”

Organic semiconductors for device applications: current trends and future prospects

“…This method was carried out on a patterned substrate, limiting the growth direction of the crystals and allowing the fine control of the crystal location and orientation over a wide area. In a subsequent experiment [457], an SiO 2 -coated Si substrate was patterned into wetting/dewetting regions using OS solution [456][457][458][459] as mentioned earlier. The wetting regions were defined by standard photolithography followed by Cytop™ spin-coating and annealing at 90°C.…”

“…There are two methods of inkjet printing in practice, namely, single-droplet printing and multiple-drop printing [459,688,689]. In single-drop printing, each droplet acts as an individual functional deposit, whereas, in the multiple droplets, a continuous film covering the whole area between the source and the drain electrodes forms the active channel.…”

Localizing trapped charge carriers in NO2 sensors based on organic field-effect transistors

“…This high molecular weight polymer provides mechanical robustness to the film for improved exfoliation while the device performance is not compromised, as shown in recent studies on solution blending of organic semiconductors with organic insulating polymers. [13][14][15][16][17] Thin films were made by spin coating a blend containing 3.6 mg/ml of ActivInk N1400, filtered with a 5 lm filter, and 18 mg/ml polystyrene in chloroform. The perylene bisimide films were annealed in vacuum at 110 C for 1 h to remove residual water and solvents.…”