What is the purpose of a laboratory hot press in the encapsulation stage of solar cell assembly? Ensure Hermetic Seals

A laboratory hot press acts as the critical bonding agent in the final stages of solar cell assembly. By applying simultaneous, precise pressure and heat—typically around 125°C—it melts thermoplastic gaskets to fuse the photoelectrode and counter electrode together. This process creates a permanent, airtight enclosure essential for the device's operation.

The hot press safeguards the solar cell's lifespan by creating a hermetic seal around the internal electrolyte. By activating a thermoplastic gasket, it prevents the evaporation of vital solvents and blocks the intrusion of air, ensuring long-term stability and consistent performance.

The Mechanics of Encapsulation

Simultaneous Heat and Pressure

The effectiveness of the hot press lies in its dual-action approach. It does not simply heat the components; it applies mechanical force while maintaining a specific temperature. This ensures the sealing material flows evenly and adheres completely to the substrates.

Activation of Thermoplastic Gaskets

The process relies on specialized thermoplastic gaskets, such as Surlyn. At standard operating temperatures of approximately 125°C, these gaskets transition from a solid to a viscous state. This phase change allows the material to bond securely between the photoelectrode and the counter electrode.

Why Hermetic Sealing is Non-Negotiable

Preventing Electrolyte Loss

Many solar cell architectures rely on internal liquid electrolytes to function. Without the robust seal provided by the hot press, these volatile solvents would evaporate rapidly. Solvent loss leads to the device drying out, resulting in immediate performance degradation.

Blocking Environmental Contamination

The encapsulation process is a two-way barrier. While it keeps the electrolyte inside, it also prevents external air and moisture from penetrating the cell. Environmental contaminants can react with internal components, causing irreversible chemical instability.

Operational Precision and Constraints

Temperature Sensitivity

Success depends on strict adherence to the melting point of the gasket material. If the temperature drops below the target (e.g., 125°C), the bond will be incomplete and the seal will fail. Conversely, excessive heat could damage other heat-sensitive layers within the cell structure.

The Pressure Balance

The application of pressure requires a delicate balance. Insufficient pressure will fail to create a hermetic seal, leaving gaps for air infiltration. However, excessive pressure risks fracturing the fragile glass electrodes used in the assembly.

Making the Right Choice for Your Goal

To ensure a successful encapsulation process, you must calibrate your equipment based on your specific assembly requirements.

• If your primary focus is longevity: Ensure your hot press maintains a consistent temperature of 125°C to fully melt the Surlyn and guarantee a hermetic barrier against solvent evaporation.
• If your primary focus is mechanical yield: Prioritize precise pressure control to flatten the gasket uniformly without cracking the electrode substrates.

Precision during the hot press stage is the single most important factor in securing the long-term chemical stability of your solar cell.

Summary Table:

Feature	Specification/Requirement	Role in Encapsulation
Temperature	Typically ~125°C	Melts thermoplastic gaskets (e.g., Surlyn) for bonding
Pressure	Controlled mechanical force	Ensures uniform gasket flow and substrate adhesion
Sealing Type	Hermetic / Airtight	Prevents solvent evaporation and blocks air/moisture
Substrates	Photoelectrode & Counter Electrode	Joins the two main components into a single unit
Outcome	Chemical Stability	Safeguards solar cell lifespan and device performance

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References

1. Ressa Muhripah Novianti, Syoni Soepriyanto. The Addition of C, Zn-C and Sn-C on Anatase Titanium Dioxide (TiO2) for Dye-Sensitized Solar Cells Application. DOI: 10.55981/metalurgi.2023.686

This article is also based on technical information from Kintek Solution Knowledge Base .