I. Abstract of the Paper’s Core Research

• An innovative method for fabricating all-aerosol‑based PDLC devices on a single substrate has been developed, eliminating the conventional double‑substrate sandwich structure.

Using only a single piece of optical glass as the substrate, the device is fabricated by sequentially depositing a bottom-layer transparent electrode, a PDLC liquid crystal film, and a top-layer PEDOT electrode. This approach eliminates two critical steps—spacer fabrication and vacuum sealing—and significantly streamlines the manufacturing process, thereby overcoming the challenge of laminating on curved surfaces.

• Excellent electro-optic scattering modulation performance

Under a 100 Hz AC electric field, complete scattering occurs at 0 V, while transmittance reaches saturation at 140 V, yielding a light–dark transmission contrast of 1.4. Under the optimal operating conditions of 90 V and 800 Hz, the liquid crystal relaxation time is as low as 1.3 ms, enabling high-speed switching suitable for high‑speed optical modulation applications.

• High curvature / angular substrates enable stable shaping.

PDLC pixels are directly printed onto 9.5 mm‑curvature optical lenses and prisms with a 90° apex angle, eliminating the need for specialized tooling. The equipment’s motion trajectory can be adapted to irregular optical surfaces without modification, ensuring continuous film deposition with no breaks or delamination.

• Solvent-Induced Phase Separation (SIPS)–Compatible Aerosol Process

After printing, the ethyl acetate solvent system evaporates spontaneously, in situ forming a micron‑scale liquid crystal droplet–dispersed polymer network. SEM observations reveal uniformly distributed liquid crystal domains, and top‑electrode printing does not disrupt the underlying liquid crystal’s microstructure.

• Digital, maskless, rapid customization of dimming pixels

CAD‑based free‑form design of square or strip‑shaped PDLC pixels, with electrodes and liquid‑crystal layers switching synchronously via inkjet printing, enabling the rapid prototyping of multiple optical‑element dimming prototypes in a single day.

II. Complete Preparation Process and Core Advantages of Aerosol-Jet-Printed PDLC Devices

(1) Complete Single-Substrate PDLC Printing Process

• Optical glass / lenses / prisms: ultrasonic cleaning with IPA and acetone, followed by dust-free drying;
• Aerosol‑jet‑printed PEDOT:PSS conductive ink was used to fabricate the bottom‑side transparent electrode at a printing speed of 3 mm/s, followed by room‑temperature air drying.
• Switch to PDLC composite ink (7cb liquid crystal + ternary polymer), depositing a 1.4 × 1.4 mm liquid crystal functional area at 5 mm/s, with an average film thickness of 46.8 μm.
• Re‑apply the PEDOT ink and, on top of the liquid crystal layer, perform edge‑printing of the top electrode with a 200 μm margin to prevent short circuits.
• At room temperature, the solvent naturally evaporates, completing SIPS phase separation without the need for high-temperature baking, allowing direct calibration of electro-optical performance.

(II) Five Core Process Advantages (Comparison of Lamination Lithography vs. Spin Coating)

• Single-substrate integrated molding completely eliminates the limitations of a double-glass sandwich structure.

Traditional processes require two ITO substrates assembled into a cell; AJP, by contrast, can fabricate a complete device using only a single optical substrate, and lenses, prisms, and curved optical components can be integrally incorporated with the dimming layer in situ.

• The non-contact mist beam is compatible with optical surfaces of any curvature, angular edges, and irregular shapes.

A printing tolerance of 3–5 mm ensures uniform film deposition on curved surfaces and at right-angle bends, whereas spin coating and photolithography are suitable only for flat, planar substrates.

• Continuous switching among multiple inks, with a single process step completing both the electrode and the liquid crystal layers.

The same device sequentially prints the conductive layer and the liquid-crystal functional layer, eliminating the need for transfer or lamination; the interlayer adhesion is strong, with no delamination.

• Film deposition at mild room temperature, without damaging the optical coating substrate.

No high-temperature sintering is required throughout the process, preventing thermal damage to the lens’s optical coating and ensuring compatibility with all types of optical components, whether made of resin or glass.

• Maskless digital rapid prototyping with flexibly adjustable pixel sizes.

No photolithography mask is required, and PDLC pixel size and arrangement can be customized on demand, reducing the optical system prototyping cycle by 90%.

III. Five Core Technological Innovations of This Study

Innovation 1: Innovatively fabricating a fully printed PDLC architecture based on single‑base, solvent‑borne sol–gel technology.

Innovation 2: An in-situ liquid-crystal phase-separation system of SIPS adapted to aerosols

Innovative 3D printing solution for full‑field conformal fabrication of high‑curvature lenses and right‑angle prisms

Innovation 4: Low-Voltage Millisecond-Scale High-Speed Electro-Optic Modulation System

Innovation 5: Conductive Polymer Top-Electrode-Compatible Process

IV. Current Industry Challenges in the Process and Corresponding Breakthrough Solutions

Challenge 1: Conventional PDLC relies on a double-glass sandwich structure, making it impossible to fabricate curved optical components.

Challenge 2: Spin coating and photolithography are only suitable for planar surfaces; they cannot achieve uniform film deposition on concave or convex optical components.

Challenge 3: The deposition of a conductive film on the liquid crystal layer can easily disrupt the microdomain structure and reduce the modulation contrast.

Challenge 4: The lamination process for multilayer components is complex, resulting in extremely high costs for small-batch optical samples.

Challenge 5: ITO rigid electrodes cannot conform to curved surfaces and are prone to cracking and open circuits.

V. Future Diversified Industrial Application Scenarios

• In-vehicle AR curved optical lens dimming

• Wavefront‑tunable optical elements for laser systems

• Industrial Intelligent Curved Observation Window

• Airborne miniature optical observation window

• High-Performance Optoelectronics Laboratory Rapid Prototyping Platform

Figure 1. Cross-sectional schematic illustrating the operating principle of PDLC: (a) In the absence of an alternating electric field, the liquid crystal droplets are randomly oriented, causing scattering of transmitted light; (b) Upon application of an alternating electric field, the liquid crystal molecules within the droplets align along the direction of the electric field, rendering the PDLC optically transparent and eliminating light scattering.

Figure 2. Schematic diagram of the aerosol jet deposition head.

Figure 3. Schematic cross-section of the printed device structure. Relative dimensions are not to scale.

Figure 4. Schematic diagram of the experimental setup: (a) Transmittance measurement; (b) Cross‑polarized transmitted light and relaxation time measurement.

Figure 5. Cross-polarized optical microscopy images of the PDLC: (a) without an applied AC voltage; (b) with an applied AC voltage of 140 V.

Figure 6. (a) shows the SEM cross-sectional image of the PDLC film on a copper substrate. The trace of the PDLC cross-section profile was obtained by applying a grayscale threshold to the PDLC surface (blue line) and drawing a straight line along the copper back‑substrate interface (orange line). (b) illustrates the cross-sectional configuration of the test sample as mounted in the SEM imaging holder.

Figure 7. Scanning electron microscope (SEM) image of cracks at the PEDOT:PSS electrode on the upper side. The liquid-crystalline domains are clearly visible beneath it.

Figure 8. (a) Transmittance as a function of applied voltage at four different frequencies. (b) Normalized values of the repolarization signal relative to the off-state repolarization signal, plotted against applied voltage for four distinct voltage frequencies. (c) Scattered light intensity measured at a viewing angle of 50°, normalized and shown as a function of applied voltage frequency, compared with the scattered intensity in the off state. (d) Relaxation times of the PDLC as a function of frequency under five different applied voltages.

Figure 9. (a) Device structure printed on a lens with a diameter of 9.5 mm and a focal length of 10 mm; (b) in the light-transmitting, transparent state; (c) in the scattering state.

Figure 10. (a) Schematic diagram of the overall structure of the prism, with a reference schematic printed for guidance. The red rectangular region corresponds to the portions shown in (b) and (c); (b) depicts the device in the off state, while (c) depicts it in the on state.