Chalcogenide glass-ceramics with photoelectric properties and method for the manufacture thereof
Chalcogenide glass-ceramic having, for example, the following composition GeSe 2 —Sb 2 Se 3 —CuI, this glass-ceramic comprising at least one crystalline phase, characterised in that the crystallisation rate and the dimensions of the crystals in the crystalline phase are such that the crystals are substantially in contact with each other in such a way that this crystalline phase has an electrical conductivity greater than or equal to 10 −4 s·cm −1 which increases under lighting due to the creation of charge carriers within the crystalline phase.
1. A chalcogenide glass-ceramic, comprising:
at least one crystalline phase; and
a composition comprising, as a molar %,
Ge + Sn + Pb
3-25
Sb + In + As + Bi
10-35
Se + Te
40-65
M
2-17
X
2-17
where M is Cu, X is a halogen, and a sum of all the molar percentages of the composition is equal to 100,
wherein a crystallisation rate in the crystalline phase and dimensions of crystals in the crystalline phase are such that the crystals are substantially in contact with each other,
wherein the crystallisation rate in the crystalline phase and the dimensions of the crystals in the crystalline phase are such that the crystalline phase has an electrical conductivity greater than or equal to 10 −4 s·cm −1 , and
wherein the electrical conductivity increases under lighting due to a creation of charge carriers within the crystalline phase.
2. The glass-ceramic according to claim 1 , wherein the composition is selected from the group consisting of GeSe 2 —Sb 2 Se 3 —CuI, SnSe 2 —Sb 2 Se 3 —CuI, PbSe 2 —Sb 2 Se 3 —CuI, GeSe 2 —As 2 Se 3 —CuI, GeSe 2 —In 2 Se 3 —CuI, GeSe 2 —Bi 2 Se 3 —CuI, GeTe 2 —Sb 2 Se 3 —CuI, GeSe 2 —Sb 2 Se 3 —CuCl, and GeSe 2 —Sb 2 Se 3 —CuBr.
3. The glass-ceramic according to claim 1 , wherein the composition comprises, as a molar %,
Ge
3-25
Sb
10-35
Se
40-65
Cu
2-17
I
2-17
where the sum of all the molar percentages of the composition being equal to 100.
4. The glass-ceramic according to claim 1 , wherein the composition is free from one or more elements selected from the group consisting of Ga, S, Cs, Zn, Cd, Rb, Na, K, B and La.
5. The glass-ceramic according to claim 1 , wherein the composition is GeSe 2 —Sb 2 Se 3 —CuI, and
wherein the respective molar percentages of the composition are:
GeSe 2
30-50
Sb 2 Se 3
30-50
CuI
10-30.
6. The glass-ceramic according to claim 1 , wherein the charge carriers created within the crystalline phase generate one or more photocurrents selected from the group consisting of a p-type photocurrent, a n-type photocurrent, and a p-and-n-type photocurrent.
7. The glass-ceramic according to claim 1 , wherein the crystallisation rate of the crystalline phase is greater than 50% in volume.
8. A method for producing a glass-ceramic, from a chalcogenide glass wherein the composition comprises, as a molar %,
Ge + Sn + Pb
3-25
Sb + In + As + Bi
10-35
Se + Te
40-65
M
2-17
X
2-17
wherein M is a transition metal such as Cu and X is a halogen such as I, Cl or Br, and the sum of all the molar percentages of the composition is equal to 100,
said method comprising:
subjecting the glass to a heat treatment a duration and time whereof are determined to create at least one crystalline phase in the glass, the crystallisation rate and the dimensions of at least some crystals of the crystalline phase being such that the crystals are substantially in contact with each other in such a way that this crystalline phase has an electrical conductivity greater than 10 −4 s·cm −1 , which increases under lighting due to the creation of charge carriers within the crystalline phase.
9. The method according to claim 8 , further comprising one or more of the following additional steps:
i) selective chemical etching of the glass-ceramic with a view to increasing a specific surface area thereof; and
ii) grinding of the glass-ceramic to increase the specific surface area thereof.
10. The method according to claim 8 , wherein the duration of the heat treatment is between 1 and 10 hours, and/or a temperature of the heat treatment is greater by more than 10° C. than a glass transition temperature of the glass.
11. The method according to claim 8 , wherein the duration of the heat treatment is greater than 1 hour so that the crystalline phase can generate a p and n type photocurrent.
12. A product chosen from a photovoltaic cell, means for decomposing or processing a chemical or biological substance, wherein the product comprises at least one glass-ceramic according to claim 1 .
13. The glass-ceramic according to claim 1 , wherein the composition is GeSe 2 —Sb 2 Se 3 —CuI, and
wherein the respective molar percentages of the composition are:
GeSe 2
35-45
Sb 2 Se 3
35-45
CuI
15-25.
14. The glass-ceramic according to claim 13 , wherein the respective molar percentages of the GeSe 2 —Sb 2 Se 3 —CuI composition are:
GeSe 2
40
Sb 2 Se 3
40
CuI
20.
15. The glass-ceramic according to claim 1 , wherein the crystalline rate of the crystalline phase is greater than 70% in volume.
16. The glass-ceramic according to claim 1 , wherein the crystalline rate of the crystalline phase is greater than or equal to 80% in volume.
17. The glass-ceramic according to claim 1 , wherein the halogen is selected from the group consisting of I, Cl, and Br.
18. The glass-ceramic according to claim 1 , wherein the halogen is I.
19. The glass-ceramic according to claim 1 , wherein the composition is GeSe 2 —Sb 2 Se 3 —CuI.