Moisture barrier for photovoltaic cells

1. A process for sealing a multilayer article comprising:

(a) providing a multilayer article to be sealed wherein said article comprises a photoactive layer disposed on a length of flexible substrate;

(b) applying a sol-gel layer to the outermost layer of said article; and

(c) heating the sol-gel layer with one or more pulses of radiation to cure the sol-gel layer into a glass layer without substantially affecting other layers, wherein the radiation is from a radiation source having emission spectrum in the range of from 200 to 1000 nm and each of the one or more pulses has a duration in the range of 1 to 1000 microseconds.

2. The process of claim 1 wherein i) said photoactive layer comprises CIGS, CIS or CZTS-Se, and ii) said glass layer is a borosilicate glass layer comprising SiO 2 , Al 2 O 3 , Na 2 O, and B 2 O 3 , and optionally one or more oxides selected from the group consisting of MgO, K 2 O, CaO, PbO, GeO 2 , SnO 2 , Sb 2 O 2 and Bi 2 O 3 .

3. The process of claim 1 wherein said glass layer has a generally uniform thickness in the range of from about 50 nm to about 2000 nm.

4. The process of claim 1 wherein the sol-gel layer is applied by spraying.

5. The process of claim 1 wherein the outermost layer is a film of Al 2 O 3 .

6. A process for making a photovoltaic device with improved resistance to moisture degradation comprising:

1) providing a photovoltaic device comprising (i) a substrate comprising a length of flexible material, and (ii) a set of multiple layers comprising a photovoltaic device disposed on a section of said substrate wherein the top layer of the set of multiple layers is a film of Al 2 O 3 ;

2) continuously moving the photovoltaic device past at least one sol-gel deposition source;

3) depositing a sol-gel layer onto the top layer of said photovoltaic device; and

4) heating the sol-gel layer with radiation to cure the sol-gel layer into a glass layer without substantially affecting other layers of the device, wherein the radiation is from a radiation source having emission spectrum in the range of from 200 nm to 1000 nm and each of the one or more pulses has a duration in the range of 1 to 1000 microseconds.

7. The process of claim 6 wherein i) said photovoltaic device is selected from the group of CIGS, CIS and CZTS-Se devices and ii) said glass layer is a borosilicate glass layer comprising SiO 2 , Al 2 O 3 , Na 2 O, and B 2 O 3 , and optionally one or more oxides selected from the group consisting of MgO, K 2 O, CaO, PbO, GeO 2 , SnO 2 , Sb 2 O 2 and Bi 2 O 3 .

8. The process of claim 6 wherein said glass layer has a generally uniform thickness of from 50 nm to 2000 nm.

9. The process of claim 6 wherein the sol-gel layer is applied by spraying.