Table of ContentsIntroductionOpportunities in Flexible Display MaketBIPV: The Future of Solar and Flexible Substrates?R2R: First for FlexibleMaterials for Flexible Substrates: Plastics, Metals and BeyondOther Possible SubstratesAbout Nanomarkets
Flexible electronics have attracted a lot of interest recently. Theoretically, they offer a large number of benefits for lightings, displays, solar panels and sensors. Each of these applications need different strategic thinking about the right flexible substrate to use, but there is also an important commonality which NanoMarkets believes will create a vibrant market for flexible substrates of various varieties.
Opportunities in Flexible Display Maket
Nanomarkets believe that there are no commercially available flexible displays as yet, though it may have potential for real world applications. The key application of flexible display will be to allow portable displays that can be plugged into a cell phone to work as an IT tool or video device. The first real rollable displays will mostly be OLED displays, since OLEDs can offer excellent color, while the most common e- paper technologies are color-challenged.
Substrates for flexible displays may not be in high demand in terms of durability, at least at first when they are used with cell phones, as cell phones generally last between one and two years. However, optical and electrical requirements for substrates used in displays may be stricter.
BIPV: The Future of Solar and Flexible Substrates?
Flexible substrate may find more applications in the building integrated PV (BIPV) sector. Though the solar industry is currently going through a weak phase, Nanomarkets believes that BIPV has a strong future due to the following reasons:
- BIPV can introduce a new aesthetic that will move into larger addressable markets and
- BIPV can share the cost of the siding functionality and roofing or PV functionality on a common substrate.
The following points need to be noted as far as the flexible substrate market is concerned:
- BIPV substrates must be conformable and must be flexible. This ensures it looks good as well as can be installed conveniently as building fabrics are mostly not square nor are even and may be flexible themselves.
- Flexible solar panels can be easier to transport and install, especially in building integrated PV applications such as roofing and window laminates.
- Even if the solar sector is going through a bad phase, the solar, flexible BIPV is a niche-like real product that will truly have great demand in the years to come.
There are only certain kinds of PV that can ever be flexible:
- Crystalline silicon is used as both a substrate and an absorber layer in the PV industry. Flexible silicon substrates are still far from reality and there are very few materials that are less flexible than crystalline silicon.
- Flexible BIPV involves either (inorganic) thin-film PV (TFPV), organic PV (OPV) or dye-sensitized cells (DSC).
- However, OPV and DSC cannot match the conversion efficiency and durability of crystalline silicon or inorganic thin-film PV.
- Within the TFPV space, the conversion efficiencies are much higher than for OPV/DSC, and the thin-film nature of TFPV means flexibility to a large degree. CIGS is a TFPV material having a high potential for flexible BIPV. However, glass is the most frequently used substrate material for TFPV in general.
R2R: First for Flexible
BIPV and displays need flexibility that can be sold to customers, flexible substrates are used for roll-to-roll (R2R) manufacturing processes
- Coating or printing is normally used in these processes, and since less expensive fabrication equipment is used and there is less material wastage, it is cost-effective. In addition, R2R processing is normally associated with room temperature processing.
- R2R processes often lead to fabricated devices that have lower performance than equivalent devices that are fabricated using the standard equipment/processes associated with traditional semiconductor manufacturing.
R2R is important in the context of flexible substrates is that it represents a convenient entry point for a firm interested in selling flexible substrates. An R2R process only requires a flexible substrate and a viable process. Though silicon wafers will possibly hold a performance advantage for the foreseeable future, R2R printing can enable a new class of disposable devices for packaging, labels, and similar applications.
Materials for Flexible Substrates: Plastics, Metals and Beyond
Flexible substrates have been categorized into metal foils and polymer films:
- Metal foils like aluminum and stainless steel are more heat resistant and less easy to deform than polymers while still offering high flexibility. They also offer a higher level of barrier protection for the rear side of the PV cell versus polymer films. Metal films are the substrate of choice for aerospace applications of PV. Metal foils are a mature product that also has a lot of potential for thinning and cost reduction.
- But polymer films are also used as substrates for flexible PV, although they need either low-temperature processing or a high-temperature polymer like polyimide.
Polymer films can be made very thin and must become a much smaller proportion of total device cost over time, especially if process development allows cheaper, less temperature-tolerant plastics to be used.
Other Possible Substrates
Other possible contenders for substrates for flexible PV include the following:
- The most likely contender is a new type of flexible glass that companies including Corning and Schott have developed. These ultrathin sheets must remain impermeable and heat tolerant as rigid glass panes while allowing a level of flexibility. However, these materials are not yet viable options for thin-film PV.
- Other new materials for flexible substrates are likely to be applied in more specialized markets that include sensors of various kinds. Here one may require flexible substrates as paper and textiles.
As has been seen, different flexible electronics/flexible PV applications have a range of requirements and these different needs affect the choice of flexible electronics:
- Metal foils and plastics are less costly than crystalline silicon or glass. These cost advantages will add on even for displays or PV panels that have to be installed in rigid frames
- In other situations, the substrate flexibility enhances the device performance in some way by decreasing installation and transportation costs.
The range of demands may place different constraints on the substrate:
- At one end of the spectrum, one finds thick foils with a limited bending radius along only one axis at a time. At the other, there are materials that may crumple or stretch in three dimensions.
- Some applications need only that the devices be able to overcome the rigors of manufacturing and shipping on the way to a rigid, final installation. The device must be able to tolerate repeated cycles of bending, stretching, or crumpling.
- Suitability for a specific application will be based on the mechanical and electrical qualities of the substrate, but also on optical properties, permeability to air and water vapor, and cost.
NanoMarkets is a leading provider of market research and industry analysis of opportunities within advanced materials and emerging energy and electronics markets. Since the firm’s founding, NanoMarkets has published over one hundred comprehensive research reports on emerging technology markets. Topics covered have included OLED displays, lighting and materials, thin-film electronics, conductive inks, transparent conductors, renewable energy, printed electronics and other promising technologies. Our client roster is a who’s who of companies in specialty chemicals, materials, electronics applications and manufacturing.
This information has been sourced, reviewed and adapted from materials provided by NanoMarkets.
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