Slot-die coating for solar cell research & scale-up
Why slot-die coating matters in solar
Silicon has set the standard for reliability; however, single-junction silicon is approaching its practical ceiling. Perovskite thin films pave the way forward, including tandems that increase energy yield without altering the module footprint.
Typical coating challenges
Solar teams face a consistent set of hurdles, from initial samples to mini-modules.
- Uniformity in the area. Maintaining thickness consistency across large wafers, sheets, or web widths is crucial for optimal device performance and yield.
- Solvent and drying control. Perovskite crystallization responds to drying kinetics. OPV morphology depends on the solvent blend and the temperature window. Tandems add interlayer coordination.
- Stability during processing. Moisture, UV, and heat can degrade layers if proper drying and handling procedures are not controlled.
- Reproducibility. Environmental drift and ink variations can derail repeat runs, especially in stacked devices.
- Material use. Expensive inks and multi-junction stacks magnify losses from overspray and rework.
FOM Technologies machines
Roll-based
Sheet-based
Roll-to-roll
What layers to coat with slot-die
Slot-die coating is suitable for both single-junction and tandem architectures on rigid and flexible substrates.
- Perovskite p-i-n stacks. Transport layers, the perovskite absorber, and encapsulation layers. Typical thickness ranges from tens to hundreds of nanometers, depending on the layer.
- OPV devices. PEDOT:PSS, BHJ active layers, and interlayers for flexible or rigid modules.
- All-perovskite or perovskite–silicon tandems. Precision layer stacking with recombination and contact layers, tuned for two-terminal or four-terminal designs.
If your work involves semi-transparent cells for BIPV, lightweight, flexible modules, or web-based encapsulation and barrier films, slot-die supports those layers as well.
Advantages of slot-die coating for solar teams
Here’s what slot-die adds to your lab and pilot workflows.
- Uniform films for consistent device metrics
- Lab to pilot continuity using the same coating principle and heads
- Low waste since material is pre-metered onto the substrate
- Repeatable, recipe-driven process with traceability
- Clean interfaces for tandems and other multilayer stacks
- Compatible with rigid and flexible substrates and complex layer sequences
High-efficiency tandems benefit directly from this control. In 2T tandems, both sub-cells share contacts and must be current-matched. In 4T, each cell runs independently. Slot-die helps by laying down repeatable transport, recombination, and contact layers across large areas.
How we help you move faster
We bridge research and scalable production with precise hardware, recipe-driven software, and direct support from our PhD scientists. Our systems are built for uniform, reproducible coatings on both sheet and web formats, which shortens the path from single cells to mini-modules and pilot lines.
Stability is the main hurdle. We support encapsulation trials, controlled drying, and interface tuning so device lifetime improves with every run.
Partnering with us also means you get to work with the industry’s largest in-house team of PhD-level material scientists, who share technical expertise and practical insights grounded in real-world coating applications.
We also collaborate with leading institutions to provide access to world-class training and test facilities for customer-specific workshops. These sessions provide new users with a hands-on introduction to the full scope of precise, scalable thin-film depositions for numerous applications.
QD Solar – Working towards large-area photovoltaics
QD Solar is advancing large-area perovskite photovoltaics with a process built for manufacturing. In early 2023, the team achieved a third-party validated 23.2% PCE on slot-die coated single-junction cells and 24% by spin coating, narrowing the usual gap between research and scalable coating. The record slot-die result was produced on a FOM vectorSC, highlighting the value of reproducible, recipe-driven control for moving from lab devices to larger formats.
“Comparing both technologies, slot-die coating is actually the better approach for large-area coating with exceptional homogeneity. I think, over time we’ll see the gap between the two technologies closing, and eventually, we’ll probably see slot-die coating come out ahead.”
– Dr. Sjoerd Hoogland, co-founder and CTO of QD Solar.
Challenge
Scale high-efficiency perovskite cells from small areas to large-area manufacturing without losing uniformity or repeatability.
Approach
Use slot-die coating on FOM vectorSC to lock in coating conditions that can be transferred across teams and sites, then tune drying and layer interfaces for consistent film quality.
Outcome
23.2% PCE, independently validated, on slot-die coated cells with results approaching spin-coat records. The team views slot-die as the more suitable path for uniform, large-area production and is working toward achieving stability and scale-up.
Advanced coating equipment for solar cell R&D
Slot-die coating technology advances solar R&D by enabling highly precise, uniform coatings that optimize performance, minimize material waste, and lower production costs. You gain scalability from lab to production, maintaining quality consistency across stages and accelerating development timelines.
At FOM, we extend these benefits through an integrated approach that combines cutting-edge systems, refined processes, and deep technical insight, delivering unmatched value beyond standard solutions.
Precision-engineered hardware excellence
With over a decade exclusively dedicated to slot-die coating, we at FOM deliver hardware precision that defines industry standards. Slot-die heads are built from the highest-quality 316L stainless steel for outstanding corrosion resistance, mechanical durability, and thermal stability under demanding conditions. We use high-quality servo motors to ensure vibration-free movement of the chuck and high-precision pumps for optimal control of wet layer thickness.
The most cost-effective way to start scaling your research
FOM Technologies’ product lineup supports solar cell researchers from lab work to pilot-scale production. Start with a compact entry system, such as the FOM nanoRC, or upgrade to a higher-spec FOM alphaSC. Both provide a solid platform for tuning ink formulations and wet film thickness before scale-up. These tools are well-suited for small-batch layer trials, including transport layers, absorbers, and interlayers. With integrated drying options, the same setup scales from small test coupons and single cells to double-sided coatings and mini-modules.
Technical support & application expertise
FOM Technologies is partnering with leading institutions worldwide to provide access to unrivaled training facilities and instruction. Our training sessions provide new users with the opportunity to jump-start their knowledge with a hands-on introduction to all aspects of precise, continuous, and scalable thin-film production via slot-die coating.
During these extensive training sessions, experienced users will also be able to sharpen their skills, fill knowledge gaps, and discuss their most pressing challenges with world-leading instructors and application experts.
Download our free application insights to discover how precision coating accelerates solar breakthroughs
From perovskite to tandem and OPV solar cells, energy harvesting technologies demand precision, scalability, and reproducibility. This application insight explores how FOM Technologies’ slot-die coating solutions empower researchers to create high-efficiency, multilayer solar devices with minimal material waste and seamless scale-up from lab to pilot.
Discover how our tools are accelerating real-world solar innovation — from breakthrough thin films to certified record efficiencies.
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