The Solar Coating Platform from GM is a unique modular coating/printing platform. The system is designed to assist upscaling from lab trials to real production style runs. It can function both as an R&D system and a production machine making it the ideal bridge between two worlds. The design allows for a variety of roll-to-roll coating and printing experiments. It is applicable to any solution-processable material – organic, perovskite and other related PV technologies, OLED, LEC and many more.
Universities and companies such as RISØ Denmark, DTU Denmark, ZAE Germany, New Castle University Australia, INES France, infinityPV.com are among the users of this coating platform.
Learn more about this technology, read the full scientific article:
Fast Inline Roll-to-Roll Printing for Indium-Tin-Oxide-free Polymer Solar Cells Using Automatic Registration
GM manufactures a wide range of solar OPV coating equipment. Figure 0 shows a multi-process coater with 3x slot dies heads, IR/HOT air ovens. Flexo coating and lamination. This line has GM's "one side drive" system. The system ensures that the web is only touched by idle rollers on one side. Special vacuum suction roller grips the web from the backside and transports it downstream.
All sections have an air management system. In this way, the atmosphere inside the unit can be controlled. In some compartments, an inert gas can be used to optimize processes.
Figure 1. R2R printing and coating machine for organic solar cells with (A) unwinder, (B) edge guide, (C) web cleaning, (D) corona treatment, (E) flexo printing unit, (F) slot-die station, (G) hot-air dryer, (H) rotary screen printing unit, (I) hot-air dryer, and (J) rewinder.
See video from ZAE university here:
Organic solar cells by infinityPV - fast roll-to-roll (R2R) printing & coating
See how Mini R2R coater is in use at DTU in Denmark:
Organic solar cells have the advantage to be fully solution-processable using printing and coating methods. The processing has been shown in labs on a variety of different substrates other than rigid glass, such as plastic foil (PET, PEN, barrier) or metal foil. The fastest fabrication can be achieved using full roll-to-roll (R2R) processes in a machine as shown in Figure 1. Companies such as infinityPV.com employing ambient R2R printing and coating methods for the fabrication of flexible organic solar cells as shown in the video on the movie slider.
Different coating and printing processes can be used and will be described in more detail in the following sections
Further important processing units for the fabrication of functional devices on foil are pre-treatment tools such as corona or plasma to increase the surface energy of the substrate. It is used to improve wetting and adhesion of the ink (e.g. silver ink) to the bare substrate surface. To remove dust particles and impurities from the surface prior to printing a web cleaning station is used.
After the actual deposition of the liquid ink, the wet layer has to be dry before getting in contact with the roller. Hot air ovens are typically used and can be supported by infrared dryers. The maximum drying temperature is limited by the substrate material (e.g. 130-140°C for PET). The drying time is ultimately defined by web speed and dryer length.
R2R fabrication strategies
Organic solar cells are multilayer devices where each layer has a specific function such as a conductive electrode or light-absorbing active layer for charge generation. Furthermore, each of the functional layers and inks has different process requirements in the final device such as layer thickness and drying time. Each ink has to be optimized for a specific processing method and vice versa. The final process parameters are often very different with respect to speed and drying time or temperature.
Figure 2. Discrete processing.
In a discrete R2R processing workflow each functional layer is printed or coated in a separate run. All process parameters (fabrication method, ink, speed, drying) are optimized to each of the layers. A machine can be optimized to a specific layer and the required conditions or vice versa. Discrete processing is the most favourable workflow for research purposes.
Figure 3. Inline processing.
The ultimate fabrication scenario is inline processing of all layers in one machine and at the same time. The order of printing unit and dryer length would be tailored to a specific device stack while the maximum processing speed is limited by the slowest single process. A process failure in one of the layers can lead to a malfunction of the full device stack. The advantage of full inline processing is the minimized bending stress inside the R2R machine, reduced handling, and potentially much faster device completion.
A special case is an intermediate process workflow with a combination of some inline processes in an overall discrete process. Subsequent printing and coating steps with similar speed ranges and drying requirements can be combined. It has been shown to work very well for the fabrication of ITO-free organic solar cells, where front silver grids and PEDOT: PSS was inline printed, and ZnO and the active layer was inline slot-die coated in one run.
Read more here
Advanced materials and processes for polymer solar cell devices;
The rapidly expanding field of polymer and organic solar cells is reviewed in the context of materials, processes and devices that significantly deviate from the standard approach which involves rigid glass substrates, indium-tin-oxide electrodes, spin-coated layers of conjugated polymer/fullerene mixtures and evaporated metal electrodes in a flat multilayer geometry. It is likely that significant advances can be found by pursuing many of these novel ideas further and the purpose of this review is to highlight these reports and hopefully spark new interest in materials and methods that may be performing less than the current state-of-the-art in their present form but that may have the potential to outperform these pending a larger investment in effort.
Link to the book:
Please notice: Large parts of this text is copied from public web-sites of clients of GM - > RISØ, DTU and InfinityPV.
Markus Hösel - some of the text from InfinityPV.
 Hösel et. al., Energy Technology 2013 10.1002/ente.201200029
Custom size possible
|Speed from 0.01m - 32m/min. Up to 120m/min on request|
|Individual printing stations: Flexographic, flatbed or rotary screen printing and multiple slot-die coating|
|DTU OPV Slot-die coating head 330mm with Knauer & Kreutzberg high-pressure ink pump system|
|Corona treater from Vetaphone|
|Double-sided ECO Web cleaning from Teknek Ltd|
|pneumatic unwind/rewind spindles
(other sizes on request)
|Splice table with pneumatic clamps and ultrasonic web guidance|
|Based on industry quality components|
|Servo-driven for smooth web transport with closed-loop tension control|
|2 meters drying tunnel through a double pass hot-air/IR oven.
(can be extended through multiple ovens)
|Semi-cantilevered design for high stability and high-res accuracy.
Easy web access and maintenance
|Open software platform with data logging|
|Build-in remote access via the internet with self-diagnostics|
|Weigh||Less than 500kg per module|
|Dimensions (LxHxD)||2.0m x 1.6m x 1.1m. Pr. module. Standard size 2 modules