Effects of Arylene Diimide Thin Film Growth Conditions on n‐Channel OFET Performance

Abstract

A series of eight perylene diimide (PDI)‐ and naphthalene diimide (NDI)‐based organic semiconductors was used to fabricate organic field‐effect transistors (OFETs) on bare SiO2 substrates, with the substrate temperature during film deposition (Td) varied from 70–130 °C. For the N,N′‐n‐octyl materials that form highly ordered films, the mobility (µ) and current on‐off ratio (Ion/Ioff) increase slightly from 70 to 90 °C, and remain relatively constant between 90 and 130 °C. Ion/Ioff and µ of dibromo‐PDI‐based OFETs decrease with increasing Td, while films of N,N′‐1H,1H‐perfluorobutyl dicyanoperylenediimide (PDI‐FCN2) exhibit dramatic Ion/Ioff and µ enhancements with increasing Td. Increased OFET mobility can be correlated with higher levels of molecular ordering and minimization of film morphology surface irregularities. Additionally, the effects of SiO2 surface modification with trimethylsilyl and octadecyltrichlorosilyl monolayers, as well as with polystyrene, are investigated for N,N′‐n‐octyl dicyanoperylenediimide (PDI‐8CN2) and PDI‐FCN2 films deposited at Td = 130 °C. The SiO2 surface treatments have modest effects on PDI‐8CN2 OFET mobilities, but modulate the mobility and morphology of PDI‐FCN2 films substantially. Most importantly, the surface treatments result in substantially increased Vth and decreased Ioff values for the dicyanoperylenediimide films relative to those grown on SiO2, resulting in Vth > 0.0 V and Ion/Ioff ratios as high as 108. Enhancements in current modulation for these high‐mobility, air‐stable, and solution‐processable n‐type semiconductors, should prove useful in noise‐margin enhancement and further improvements in organic electronics.

High resolution NEXAFS of perylene and PTCDI: a surface science approach to molecular orbital analysis

“…5 More recently, a new class of n-type organic semiconductors, based on PTCDI derivatives, has been demonstrated capable of filling the historical gap between p-type and n-type OFETs in terms of both charge mobility and environmental stability. 6,7 Ahead of an impressive increase of the number of newly synthesized PTCDI derivatives for both OPVs 8 and OFETs, 9 the advanced modeling of perylenes is mostly focused on the intermolecular coupling geometry, 10 which affects the optical spectrum, 11 and on the structure of monolayer phases at surfaces. [12][13][14] From the experimental point of view, the spectroscopic characterization of the molecular orbitals of the free PTCDI molecule, as well as of perylene, is largely outdated or limited.…”

Electrical characterisations of plasma polyermised linalyl acetate

“…Organic Field Effect Transistors (OFETs) are an integral component of many organic electronic devices, providing the basis for logic and CMOS circuitry, as well as switching and amplification of signals. Predominantly, research on OFETs is concentrated around the semiconducting channel, where material choice and optimisation, deposition method and post-deposition treatment are heavily explored topics of scientific interest [3][4][5][6][7]. p-Type materials are well explored due to their high mobilities, ease of manufacture and stability in ambient environments [8], and current research has resulted in the properties of n-type materials being greatly improved [5,9,10].…”

Wet-processed n-type OTFTs utilizing highly-stable colloids of a perylene diimide derivative

“…3 (b), which is well matched with the result of DLS measurement. The rod-like shape (and/or wire shape) of particles is a typical crystal shape of PTCDI derivatives where PTDCI molecules are arranged almost perpendicularly to the long direction of crystals [29,34,37,[44][45][46]. The zeta-potential was also measured as large as -26.3 mV with the standard deviation of 10.5 mV (S3).…”

“…It, especially, has several phase transitions at relatively low temperature due to the long side alkyl chains, and the morphology of vacuum deposited films is largely changed by post-annealing treatment which also leads to the large change in the mobility of its devices [32,36,37]. It is, however, not soluble in common solvents and cannot be handled by wet-processes.…”