I. Abstract of the Paper’s Core Research

• Low-temperature inks achieve ultra-high print uniformity.

When the ink temperature is maintained at 8 °C, ultrasonic atomization yields a stable droplet concentration, and the carbon nanotube film exhibits higher density. During continuous printing for one hour, the device mobility shows a relative standard deviation of only 4%, representing the best consistency among all printed carbon‑nanotube devices reported to date.

• High-performance carbon nanotube channel, with mobility exceeding 12.5 cm²/V·s.

Low-temperature atomization reduces carbon nanotube agglomeration, while the thin film features a highly porous permeation pathway. Maskless aerosol direct-writing is employed to fabricate the channel, yielding a hole mobility of 12.5 ± 0.5 cm²/V·s—performance comparable to high-precision laboratory techniques such as spin coating and drop casting.

• Comprehensive, turnkey process stabilization solutions

① A composite ink formulated with toluene and high-boiling-point terpineol suppresses coffee-ring formation and prevents droplets from drying prematurely; ② Rapid thermal annealing (RTA) at 450 °C thoroughly removes the polymer coating on the carbon nanotube surfaces, thereby reducing inter-tube contact resistance; ③ ALD‑grown aluminum oxide encapsulation isolates the device from air and moisture, significantly mitigating device hysteresis.

• Long-term printing with no performance drift.

High-temperature ink (32 °C) exhibits a continuous decline in migration rate after one hour of printing; in an 8 °C constant-temperature system, device performance remains remarkably stable throughout operation, and after thermal equilibrium is reached, parameters across multiple batches remain highly consistent after 60 minutes, making it well-suited for automated continuous production lines.

• The process has strong versatility.

The ink‑temperature‑control strategy is compatible with both semiconductor carbon nanotube and silver nanoparticle conductive inks, enabling source–drain electrodes and the active channel to be printed in separate steps on the same equipment, thus realizing the fabrication of all‑aerosol‑based field‑effect transistors.

II. Working Principle of Aerosol Spraying & Unique Process Advantages

(1) Complete Temperature-Controlled Aerosol Printing Process

• Constant-Temperature Ink Tank : The atomization tank is externally connected to a chiller, maintaining a constant ink temperature throughout the process and eliminating viscosity and volatility fluctuations caused by temperature increases.
• Ultrasonic atomization : Constant-power oscillation of carbon nanotube ink generates uniformly sized ultrafine aerosols;
• Dual‑stream flow confinement: a nitrogen carrier gas transports the droplets, while a coaxial sheath gas isolates the nozzle inner wall, effectively preventing clogging.
• The platform undergoes uniform deposition, with multiple layers stacking to form a continuous carbon nanotube network.
• Rapid thermal annealing removes surface dispersants, aerosol-printed silver nanowire source–drain electrodes are employed, and ALD aluminum oxide encapsulation is available as an option.

(II) Five Core Technological Advantages (Compared with Inkjet, Doctor Blade, and Conventional Uncontrolled-Temperature Aerosol Technologies)

• Low-temperature atomization enhances the densification of thin films.

At high temperatures, ink solvents evaporate rapidly, leading to solute agglomeration before the droplets reach the substrate; at a low temperature of 8 °C, evaporation is slowed, enabling uniform dispersion of carbon nanotubes and a significant increase in the number of conductive pathways.

• Long-term continuous printing with stable performance and no drift.

In an uncontrolled-temperature system, the ink continuously heats up, leading to a gradual decline in atomization efficiency; in contrast, the temperature‑controlled chamber maintains stable material properties throughout, with extremely low batch-to-batch variability over one hour of continuous production.

• Significantly reduce coffee-ring defects.

High-boiling terpineol‑based ink formulation combined with a low‑temperature droplet‑coalescence mechanism ensures thorough droplet merging, resulting in a thin film with low surface roughness and reduced device leakage current.

• Fully integrated printing compatibility

The same temperature-controlled aerosol‑printing system can fabricate carbon‑nanotube active layers and silver electrodes, eliminating the need to switch between multiple sets of equipment and streamlining the production line layout.

• Compatible with both rigid wafers and flexible plastic substrates

Non-contact deposition with adjustable nozzle spacing enables the high‑consistency, large‑scale fabrication of TFTs on both silicon wafers and PI flexible substrates.

III. Key Technological Innovations of This Study

Innovation 1: Pioneered the core control mechanism for ink temperature regulation.

Innovation 2: High-Boiling-Point Additive–Modified Carbon Nanotube Ink

Innovation 3: Rapid Thermal Annealing (RTA) for Efficient Removal of Passivation Polymers

Innovation 4: Pre‑standardized mass‑production process for thermal equilibrium

Innovation 5: Alumina encapsulation suppresses air interference.

IV. Existing Process Challenges and Corresponding Solutions for Overcoming Them

Challenge 1: The rise in ink temperature causes rapid solvent evaporation, leading to carbon nanotube aggregation and a sparse thin film.

     Challenge 2: During prolonged printing, the ink temperature rises slowly, leading to a continuous decline in device mobility.

Challenge 3: Polymer coating on the carbon nanotube surface increases inter-tube contact resistance and results in reduced carrier mobility.

  Challenge 4: Single-solvent printing results in severe coffee-ring effects and uneven film thickness.

Challenge 5: Carbon nanotubes are susceptible to atmospheric moisture, leading to significant device hysteresis and poor reproducibility.

V. Future Diversified Industrial Application Scenarios

1. Large-area flexible display backplane

2. Flexible Sensing Electronics

3. Low-Cost Flexible Logic Circuits

4. Wafer-Level Carbon-Based Integrated Circuits

5. Radiation-Resistant Circuit for Extreme Environments

Figure 1. Schematic of the device architecture of a printed carbon nanotube field-effect transistor (CNT‑TFT) and the aerosol jet printing parameters. The schematic illustrates, respectively: (a) the structure of the printed CNT‑TFT, comprising silver nanoparticle (AgNP) source/drain contact layers, a substrate gate, and a semiconducting carbon nanotube channel; and (b) the ultrasonic atomizer used for aerosol jet printing—connected to a cooling system to regulate the ink bath temperature—employed for depositing carbon nanotube and silver nanoparticle thin films.

Figure 2. Film morphology and CNT‑TFT performance as functions of the CNT ink‑bath temperature. (a) Transfer characteristics of the CNT‑TFT, with the subthreshold swing shown in the inset, as a function of the ink‑bath temperature; measurements were conducted in ambient air, with a 30‑nm aluminum oxide layer deposited on the device surface to mitigate environmental effects. (b) Mobility (left axis) and the relative change σ(μh)/μh (right axis) as functions of the CNT ink‑bath temperature. (c) Threshold voltage (left axis) and the absolute change σ(μh) (right axis), both plotted against the CNT ink‑bath temperature. Each data point represents the mean ± standard deviation. (d) Optical images of the printed CNT film at different ink‑bath temperatures.

Figure 3. Relationship between the printing stability of carbon nanotube (CNT) devices and the ink bath temperature under high-vacuum conditions, aimed at minimizing environmental effects. (a, b) Transfer characteristics of CNT‑TFT devices printed at ink bath temperatures of 8°C and 32°C, respectively, over different printing durations; each data point corresponds to 7–8 CNT‑TFT devices. (c) Mobility; (d) Relative change in mobility; (e) Threshold voltage; (f) Absolute change in the channel threshold voltage of CNTs printed at 8°C (blue) and 32°C (red) for various printing times.

Figure 4. High uniformity and stability of printed carbon nanotube field-effect transistors (CNT‑TFTs). (a) Transfer characteristics of CNT‑TFTs fabricated under varying printing durations at an ink‑bath temperature of 8 °C (device surfaces coated with a 30 nm aluminum oxide layer to minimize environmental effects). (b) Mobility of the carbon‑nanotube channels prepared at different printing times (left axis) and its relative change (right axis). (c) Threshold voltage of the carbon‑nanotube channels prepared at different printing times (left axis) and its absolute change (right axis).

Figure 5. Benchmarking of CNT‑TFT performance and uniformity. The figure shows the relationship between the relative standard deviation of hole mobility in CNT‑TFTs and their mobility values. Detailed specifications of the devices compared in this figure are provided in Table S1.