Organic Ring Oscillators with Sub‐200 ns Stage Delay Based on a Solution‐Processed p‐type Semiconductor Blend

Abstract

the manufacturing processes divide naturally into two general approaches i.e., solution-processing and vacuum processing. In the former approach some or all transistor and circuit elements are deposited from solution and holds out the promise of low-cost, high-volume roll-to-roll (R2R) manufacture of circuits using, for example, inkjet [ 7 ] or gravure printing. [ 8 ] On the other hand, processes requiring vacuum evaporation of one or more component, or photolithography and dry-etching are more suited to batch-processing.Progress has been, and continues to be made, in applying mass-printing R2R processes [ 9 ] with a range of logic circuits being demonstrated [ 10 ] albeit based on singlewalled carbon nanotubes as the active material. High-speed metal patterning and barrier layer deposition are commercially used processes. R2R circuit fabrication based entirely on vacuum evaporation is, therefore, feasible. [ 11 ] For example, saturated-load unipolar ring oscillators (ROs) were produced in a R2R-compatible environment. [ 12 ] Although a stage delay of 46 µs was achieved at a high supply voltage, circuit performance was compromised by a nonoptimal design purposely limited to the resolution and registration capability of a high-speed metal printing process. Nevertheless, the stage delay achieved was much shorter than previously reported for ROs produced using all-solution mass-printing processes ( Table 1 ) . [13][14][15] This refl ects the generally higher mobilities of vacuum-evaporated small-molecules [ 12 ] compared with solutionprocessed small-molecules. [ 16,17 ] Other performance-degrading features of solution R2R-processes include a relatively thick dielectric layer and relatively poor resolution. The former leads to high operating voltages. The latter reduces operating speed by restricting the source-drain gap, i.e., the channel length, L , of the OTFTs to a minimum of about 30-40 µm. Achieving a resolution below ≈10 µm to improve device speed poses a signifi cant near-term challenge for mass-printing processes. Relatively poor registration between different patterned layers is a further problem leading to undesirable parasitic effects. [ 12 ] It is not surprising, therefore, that the signifi cant improvements in organic circuit performances have been demonstrated using the higher resolution approaches derived from silicon technology. At the most basic level, this is confi ned to patterning source-drain electrodes by photolithography to achieve channel lengths of 5 µm High-frequency ring oscillators with sub-microsecond stage delay fabricated from spin-coated fi lms of a specially formulated small-molecule/host-polymer blend are reported. Contacts and interconnects are patterned by photolithography with plasma etching used for creating vias and removing excess material to reduce parasitic effects. The characteristics of transistors with 4.6 µm channel length scale linearly with channel width over the range 60-2160 µm. Model device parameters extracted using Silvaco's Universal Organic Thin Film Transistor...

Patterning an Erosion-Free Polymeric Semiconductor Channel for Reliable All-Photolithography Organic Electronics

“…To the best of our knowledge, this is the highest integration density of organic circuits prepared by photolithography or printing technology (Figure g). ,,,− ,,,, The miniaturized 15-stage RO can work effectively. It should be mentioned that the oscillation frequency (6 Hz) is lower than those of previously reported organic ROs. , This can mostly be attributed to the dramatically reduced mobility of the driver transistor on the sulfone-based OGI layer (see Figure S14). Nonetheless, benefiting from the decrease in th eparasitic capacitance after scaling down, , the miniaturized RO has six-times the work frequency of big devices.…”

“…It should be mentioned that the oscillation frequency (6 Hz) is lower than those of previously reported organic ROs. 44,45 This can mostly be attributed to the dramatically reduced mobility of the driver transistor on the sulfone-based OGI layer (see Figure S14). Nonetheless, benefiting from the decrease in th eparasitic capacitance after scaling down, 46,47 the miniaturized RO has six-times the work frequency of big devices.…”

Fabrication of ring oscillators using organic molecules of phenacene and perylenedicarboximide

“…It is shown in ref. 41 that f osc is clearly correlated with L. A smaller L in the FET blocks in each inverter of the ring oscillator provides a higher f osc . This result is explained by the theoretical model described below.…”

Tunable Two-Dimensional Patterning of a Semiconducting and Nanometer-Thin C60 Fullerene Film Using a Spatial Light Modulator

“…The field of organic electronics is in rapid development because of the easy tunability, soft and flexible nature, and facile processing of the constituent organic semiconductor (OSC). − However, the ability to pattern a nanometer-thin OSC layer with retained electronic properties is an additional critical requirement for the function, or improved operation, of a number of applications, including photodetectors, − sensors, , emissive devices, , and electronic circuits. , It is therefore not surprising that a plethora of different patterning methods, such as transfer stamping, , gravure printing, self-assembly, − cross-linking by electron and ion beams, , and photolithography using a sacrificial photoresist, , have been developed during recent years.…”