Thin-film morphology of inkjet-printed single-droplet organic transistors using polarized Raman spectroscopy: effect of blending TIPS-pentacene with insulating polymer.
We report thin-film morphology studies of inkjet-printed single-droplet organic thin-film transistors (OTFTs) using angle-dependent polarized Raman spectroscopy. We show this to be an effective technique to determine the degree of molecular order as well as to spatially resolve the orientation of the conjugated backbones of the 6,13-bis(triisopropylsilylethynyl)pentacene (TIPS-Pentacene) molecules. The addition of an insulating polymer, polystyrene (PS), does not disrupt the π-π stacking of the TIPS-Pentacene molecules. Blending in fact improves the uniformity of the molecular morphology and the active layer coverage within the device and reduces the variation in molecular orientation between polycrystalline domains. For OTFT performance, blending enhances the saturation mobility from 0.22 ± 0.05 cm(2)/(V·s) (TIPS-Pentacene) to 0.72 ± 0.17 cm(2)/(V·s) (TIPS-Pentacene:PS) in addition to improving the quality of the interface between TIPS-Pentacene and the gate dielectric in the channel, resulting in threshold voltages of ∼0 V and steep subthreshold slopes.
Department of Physics and Centre for Plastic Electronics, Imperial College London, London SW7 2AZ, United Kingdom.
David T
DT
James
B K Charlotte
BK
Kjellander
Wiljan T T
WT
Smaal
Gerwin H
GH
Gelinck
Craig
C
Combe
Iain
I
McCulloch
Richard
R
Wilson
Jeremy H
JH
Burroughes
Donal D C
DD
Bradley
Ji-Seon
JS
Kim
D016287:Computer Peripherals; D004553:Electric Conductivity; D004867:Equipment Design; D019544:Equipment Failure Analysis; D008567:Membranes, Artificial; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D009930:Organic Chemicals / Q000737:chemistry*; D017646:Organosilicon Compounds / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000295:instrumentation / Q000379:methods*; D014173:Transistors, Electronic
D008567:Membranes, Artificial; D009930:Organic Chemicals; D017646:Organosilicon Compounds; D011108:Polymers; C522282:bis(triisopropylsilylethynyl)pentacene