Method for recovering resource from CIGS thin-film solar cell

1. A method for recovering a resource from a CIGS thin-film solar cell to be recycled, the method comprising steps of:

a) providing the CIGS thin-film solar cell which includes

a front substrate,

a light absorbing unit disposed rearwardly of the front substrate, and having a CIGS photovoltaic layer which includes copper, indium, gallium, and selenide,

a first adhesive layer sandwiched between the front substrate and the light absorbing unit,

a rear substrate unit disposed rearwardly of the light absorbing unit, and including at least one rear substrate and a second adhesive layer, and

an electrical contact layer sandwiched between the light absorbing unit and the rear substrate unit, wherein a bonding force between the electrical contact layer and the light absorbing unit is smaller than a bonding force between the electrical contact layer and the rear substrate unit; and

b) subjecting the CIGS thin-film solar cell to a cooling treatment at a predetermined temperature lower than a brittleness temperature of the second adhesive layer such that the light absorbing unit is separated from the electrical contact layer as a result of a thermal strain produced between the electrical contact layer and the rear substrate unit.

2. The method according to claim 1 , wherein, in step b), the predetermined temperature is also lower than a brittleness temperature of the first adhesive layer so as to reduce a viscosity of the first adhesive layer, thereby facilitating detachment of the front substrate from the light absorbing unit.

3. The method according to claim 2 , wherein the electrical contact layer is made of molybdenum.

4. The method according to claim 1 , after step b), further comprising a step of

c) removing the first adhesive layer using a solvent so as to obtain the light absorbing unit that is recovered from the CIGS thin-film solar cell.

5. The method according to claim 4 , wherein the first adhesive layer is made of ethylene-vinyl acetate, and the solvent is a diluted HCl aqueous solution having a concentration ranging from 0.1 mol/L to 1.2 mol/L.

6. The method according to claim 4 , after step c), further comprising a step of

d) subjecting the recovered light absorbing unit to an annealing treatment at a temperature ranging from 800° C. to 950° C. in an oxygen ambient so as to remove the selenide in the light absorbing unit and to collect selenium oxide, thereby obtaining an intermediate including oxides of copper, indium, and gallium.

7. The method according to claim 6 , after step d), further comprising a step of

e) dissolving copper, indium, and gallium ions from the intermediate using an inorganic acid aqueous solution as a solvent so as to obtain a first acid solution including the copper, indium, and gallium ions.

8. The method according to claim 7 , further comprising a step of

f) subjecting the first acid solution to extraction using di(2-ethylhexyl)phosphoric acid as an eluent whilst keeping aqueous phase pH value to be not greater than 1 so as to obtain a first organic phase solution including the indium ions, and a second acid solution including the copper and gallium ions.

9. The method according to claim 8 , further comprising a step of

g) subjecting the second acid solution to extraction using di(2-ethylhexyl)phosphoric acid as an eluent whilst keeping aqueous phase pH value to be less than 7 and greater than 1 so as to obtain a second organic phase solution including the gallium ions, and a third acid solution including the copper ions.

10. The method according to claim 9 , further comprising steps of:

h) subjecting the first organic phase solution to extraction using a HCl aqueous solution as an eluent so as to obtain a first aqueous extraction including the indium ions; and

i) subjecting the second organic phase solution to extraction using a HCl aqueous solution as an eluent so as to obtain a second aqueous extraction including the gallium ions.

11. The method according to claim 10 , further comprising steps of:

j) subjecting the first aqueous extraction to chemical precipitation using ammonium hydroxide as a precipitation reagent so as to obtain a first precipitate including indium hydroxide;

k) subjecting the second aqueous extraction to chemical precipitation using ammonium hydroxide as a precipitation reagent so as to obtain a second precipitate including gallium hydroxide; and

l) subjecting the third acid solution to chemical precipitation using ammonium hydroxide as a precipitation reagent so as to obtain a third precipitate including copper hydroxide.

12. The method according to claim 10 , further comprising steps of:

m) subjecting the first precipitate to calcination so as to obtain indium oxide;

n) subjecting the second precipitate to calcination so as to obtain gallium oxide; and

o) subjecting the third precipitate to calcination so as to obtain copper oxide.

13. The method according to claim 1 , wherein, in step

b), the cooling treatment is implemented using a cooling medium selected from the group consisting of liquid nitrogen, liquid argon, liquid oxygen, liquid carbon dioxide, and combinations thereof.

14. A method for recovering a resource from a CIGS thin-film solar cell to be recycled, the method comprising steps of:

i) providing a light absorbing unit recovered from the CIGS thin-film solar cell, the recovered light absorbing unit having a CIGS photovoltaic layer which includes copper, indium, gallium, and selenide;

ii) subjecting the recovered light absorbing unit to an annealing treatment at a temperature ranging from 800° C. to 950° C. in an oxygen ambient to remove the selenide in the light absorbing unit and to collect selenium oxide, thereby obtaining an intermediate including oxides of copper, indium, and gallium;

iii) dissolving copper, indium, and gallium ions from the intermediate using an inorganic acid aqueous solution as a solvent so as to obtain a first acid solution including the copper, indium, and gallium ions; and

iv) subjecting the first acid solution to extraction using di(2-ethylhexyl)phosphoric acid as an eluent whilst keeping aqueous phase pH value to be not greater than 1 so as to obtain a first organic phase solution including the indium ions, and a second acid solution including the copper and gallium ions.

15. The method according to claim 14 , before step i), further comprising steps of:

i-1) providing the CIGS thin-film solar cell which includes

a front substrate,

the light absorbing unit disposed rearwardly of the front substrate,

a first adhesive layer sandwiched between the front substrate and the light absorbing unit,

a rear substrate unit disposed rearwardly of the light absorbing unit, and including at least one rear substrate and a second adhesive layer, and

an electrical contact layer sandwiched between the light absorbing unit and the rear substrate unit, wherein a bonding force between the electrical contact layer and the light absorbing unit is smaller than a bonding force between the electrical contact layer and the rear substrate unit;

i-2) subjecting the CIGS thin-film solar cell to a cooling treatment at a predetermined temperature lower than a brittleness temperature of the second adhesive layer such that the light absorbing unit is separated from the electrical contact layer as a result of a thermal strain produced between the electrical contact layer and the rear substrate unit; and

i-3) removing the first adhesive layer using a solvent so as to obtain the recovered light absorbing unit.

16. The method according to claim 14 , further comprising

a step of

v) subjecting the second acid solution to extraction using di(2-ethylhexyl)phosphoric acid as an eluent whilst keeping aqueous phase pH value to be less than 7 and greater than 1 so as to obtain a second organic phase solution including the gallium ions, and a third acid solution including the copper ions.

17. The method according to claim 16 , further comprising steps of:

vi) subjecting the first organic phase solution to extraction using a HCl aqueous solution as an eluent so as to obtain a first aqueous extraction including the indium ions; and

vii) subjecting the second organic phase solution to extraction using a HCl aqueous solution as an eluent so as to obtain a second aqueous extraction including the gallium ions.

18. The method according to claim 17 , further comprising steps of:

viii) subjecting the first aqueous extraction to chemical precipitation using ammonium hydroxide as a precipitation reagent so as to obtain a first precipitate including indium hydroxide;

ix) subjecting the second aqueous extraction to chemical precipitation using ammonium hydroxide as a precipitation reagent so as to obtain a second precipitate including gallium hydroxide; and

x) subjecting the third acid solution to chemical precipitation using ammonium hydroxide as a precipitation reagent so as to obtain a third precipitate including copper hydroxide.

19. The method according to claim 18 , further comprising steps of:

xi) subjecting the first precipitate to calcination so as to obtain indium oxide;

xii) subjecting the second precipitate to calcination so as to obtain gallium oxide;

xiii) subjecting the third precipitate to calcination so as to obtain copper oxide.

20. The method according to claim 15 , wherein, in step i-2), the cooling treatment is implemented using a cooling medium selected from the group consisting of liquid nitrogen, liquid argon, liquid oxygen, liquid carbon dioxide, and combinations thereof.