6,13-bis(triisopropylsilylethinyl)pentacene commonly known as TIPS pentacene.

A high-purity TIPS-Pentacene for use in organic field-effect transistors (OFETs). In stock for immediate delivery to academic institutions in Europe and other selected geographical areas outside of North America. TIPS-Pentacene is widely used as a high performance small molecule for OFET applications, with a mobility in excess of 1 cm²/Vs having being achieved in the literature. It has excellent solubility in a range of common organic solvents, and a good ambient stability - making it easy to process into devices. Ossila"s TIPS-pentacene has been produced with a purity of >99.9%.

Please note that TIPS-Pentacene is unavailable to buyers in the USA. Any incoming orders from the USA for TIPS-Pentacene will not be processed.

General Information

Product Details

Characterisation

 

OFET fabrication procedure

Abstract

We have achieved a mobility of approximately 0.92 cm²/Vs using TIPS-Pentacene for top contact OFETs with a drop casting protocol. The TIPS-Pentacene film is obtained through slow crystallisation growth at high temperature (50°C), in solvent saturated ambient, over silicon oxide substrates treated with phenyl-terminated silane molecules.

Results

The image below depicts the best performance OFET, showing how the boundaries of the crystals forming the crystallite domain have boundaries parallel to the channel length. Cracks perpendicular to the growth direction are also clearly visible. These cracks act as defects (bottlenecks for charge transport) and must be minimised in order to obtain high-performing OFETs.

 

FET measurements

The table below summarises the mobility and threshold voltage for the three PTES-treated substrates, taking an average of 75% of the 15 OFET devices to minimise the maximum and minimum outliers.

 

Drop casting details

The direction of the crystal growth, and therefore the orientation of the crystal axes (with respect to the channel length), can be controlled by imposing a preferential drying direction to the drop casted solution. This is achieved by positioning the substrate inside a Petri dish at a 3.5° angle with respect to the horizontal line of a perfectly flat hot plate. Substrates are placed inside the Petri dish in a manner such that the length of the channel is perpendicular to the receding direction of the drying solution. Drop casting is carried out using a pipette with the substrate at a temperature of 50°C. The lid was put back immediately afterwards to trap the solvent vapour and create a vapour-saturated condition inside the Petri dish.

Images below taken of thin films of TIPS-pentacene deposited by spin casting and drop casting from toluene (10 mg/ml) on SiO_2, showing the strong crystallisation behaviour in slow dried films.

Experimental

OFET device specifications

This table shows details of the substrates used in this fabrication routine.

TIPS-Pentacene Solution Preparation

• TIPS-pentacene dissolved in anhydrous toluene, 10 mg/ml, to make stock solution
• The stock solution is placed on a hotplate at 60°C for 1 hour at 1000 rpm with a magnetic stirrer
• Solution was then filtered with 0.45 µm filter into a new vial
• Required amount was diluted with anhydrous toluene to 2 mg/ml

Substrate cleaning

• 1% Hellmanex III solution in hot DI water
• Sonicate for 5 min in hot water
• Rinse twice in hot water
• IPA, Sonicate 5 min in hot water
• Rinse twice in DI water (cold)
• Store substrates in DI water
• UV Ozone treatment for 5 min

Surface Treatments

• PTES (Trichloro(phenethyl)silane) treatment: 3 mMol in toluene for 15 hrs in glove box at 90°C or, alternatively
• PTS (Trichloro(phenyl)silane) treatment: 3% in weight in toluene at 90°C for 15 hrs in glove box 
• Substrates rinsed twice in glove box with toluene, then blow dried and brought outside a glove box
• Sonicated in toluene for 10 minutes and blow dried
• Rinsed with 2 ml of acetone and blow dried
• Rinsed with 2 ml of IPA and blow dried
• Put in glove box on hotplate at 150°C for 5 min

TIPS-pentacene drop casting

• Pipetted 50 μl of TIPS solution (2 mg/ml) onto each substrate, which were sitting within a petri dish
• Covered with glass lid for 5 minutes on a hot plate at 50°C
• Hot plate switched off and left to cool down to close to room temperature
• Using cleanroom swabs wetted with toluene, wiped the substrates clean with the exception of the area over which the drain and source were to be deposited 
• Loaded the substrates into the evaporation stack for low density OFETs

Deposition of top contact gold

• Loaded Edwards Auto 306 thermal evaporator
• Evaporator left to pump down to low pressure (ca. 2 x 10^-6 mBar)
• Deposited 80 nm of gold on TIPS-pentacene-coated substrates

OFETs were measured using an Ossila Test Board for Low-Density OFETs (E222) under air.

To download the full report click here

To the best of our knowledge the technical information provided here is accurate. However, Ossila assume no liability for the accuracy of this information. The values provided here are typical at the time of manufacture and may vary over time and from batch to batch.