Electronic device module comprising an ethylene multi-block copolymer
An electronic device module comprises: A. At least one electronic device, e.g., a solar cell, and B. A polymeric material in intimate contact with at least one surface of the electronic device, the polymeric material comprising an ethylene multi-block copolymer. Typically, the polyolefin material is an ethylene multi-block copolymer with a density of less than about 0.90 grams per cubic centimeter (g/cc). The polymeric material can fully encapsulate the electronic device, or it can be laminated to one face surface of the device. Optionally, the polymeric material can further comprise a scorch inhibitor, and the copolymer can remain uncrosslinked or it can be crosslinked.
1. An electronic device module comprising:
A. At least one solar cell,
B. An encapsulant film in intimate contact with at least one surface of the solar cell and comprising a polymeric material, the polymeric material comprising a reaction product of at least: (1) an ethylene multi-block copolymer characterized by (i) a molecular fraction that elutes between about 40 C and about 130 C when fractionated using TREF, characterized in that the fraction has a block index of at least 0.5 and up to about 1 and a MWD greater than about 1.3, (ii) an average block index greater than zero and up to about 1.0 and an MWD greater than about 1.3, (iii) a melt point of less than about 125 C, (iv) a density of from less than 0.89 g/cc to greater than 0.85 g/cc, and (v) having at least one property of (a) a 2% secant modulus of less than about 150 megaPascal (mPa) as measured by ASTM D-882-02, (b) an α-olefin content of at least about 10 and less than about 80 weight percent (wt %) based on the weight of the copolymer, and (c) a Tg of less than about −35 C, (2) a vinyl silane in an amount of at least about 0.1 wt % based on the weight of the copolymer, and (3) optionally, a co-agent,
wherein the polymeric material has greater than or equal to 92% transmittance over the wavelength range of 400 to 1100 nanometers, and a water vapor transmission rate of less than about 50 grams per square meters per day (g/m 2 -day),
C. A cover sheet in intimate contact with at least a portion of the encapsulant film, and
D. A backsheet in intimate contact with at least one of the solar cell and the encapsulant film,
wherein the encapsulant film is between the cover sheet and the backsheet.
2. The module of claim 1 comprising the coagent present in an amount of at least about 0.05 wt % based on the weight of the copolymer.
3. The module of claim 2 further comprising a free radical initiator which is a peroxide.
4. The module of claim 3 in which the vinyl silane is at least one of vinyl tri-ethoxy silane and vinyl tri-methoxy silane.
5. The module of claim 1 in which the polyolefin copolymer is crosslinked such that the copolymer contains less than about 70 percent xylene soluble extractables as measured by ASTM 2765-95.
6. The module of claim 1 in which the encapsulant film is a monolayer film.
7. The module of claim 1 in which the polymeric material further comprises a scorch inhibitor in an amount from 0.01 to about 1.7 wt %.
8. The module of claim 1 in which the polymeric material further comprises a polyolefin polymer grafted with an unsaturated organic compound containing at least one ethylenic unsaturation and at least one carbonyl group.
9. The module of claim 8 in which the unsaturated organic compound is maleic anhydride.
10. An electronic device module comprising:
A. A solar cell, and
B. An encapsulant film in intimate contact with at least one surface of the electronic device and comprising a polymeric material, the polymeric material comprising an ethylene multi-block copolymer characterized by (i) a molecular fraction that elutes between about 40 C and about 130 C when fractionated using TREF, characterized in that the fraction has a block index of at least 0.5 and up to about 1 and a MWD greater than about 1.3, (ii) an average block index greater than zero and up to about 1 and a MWD greater than about 1.3, (iii) a density of from less than 0.89 g/cc to greater than 0.85 g/cc, and (iv) having at least one property of (a) a 2% secant modulus of less than about 150 megaPascal (mPa) as measured by ASTM D-822-02, (b) a melt point of less than about 125 C, (c) an α-olefin content of at least about 10 and less than about 80 weight percent (wt %) based on the weight of the copolymer, and (d) a Tg of less than about −35 C,
wherein the polymeric material has greater than or equal to 92% transmittance over the wavelength range of 400 to 1100 nanometers, and a water vapor transmission rate of less than about 50 grams per square meters per day (g/m 2 -day),
C. A cover sheet in intimate contact with at least a portion of the encapsulant film, and
D. A backsheet in intimate contact with at least one of the solar cell and the encapsulant film
wherein the encapsulant film is between the cover sheet and the backsheet.
11. The electronic device module of claim 1 in which the encapsulant film is a co-extruded film in which at least one outer skin layer (i) does not contain peroxide for crosslinking, and (ii) is the surface which comes into intimate contact with the module.
12. The electronic device module of claim 11 in which the co-extruded film comprises at least three layers.
13. The electronic device module of claim 12 in which a core layer of the encapsulant film contains peroxide.
14. The electronic device module of claim 1 in which the encapsulant film fully encapsulates the solar cell and the backsheet is in intimate contact with at least a portion of the encapsulant film.
15. The electronic device module of claim 1 in which the backsheet is in intimate contact with at least one surface of the solar cell.
16. The electronic device module of claim 10 in which the encapsulant film fully encapsulates the solar cell and the backsheet is in intimate contact with at least a portion of the encapsulant film.
17. The electronic device module of claim 10 in which the backsheet is in intimate contact with at least one surface of the solar cell.