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US-20260125810-A1 - ZnTiN2 AS A CARRIER-SELECTIVE PROTECTIVE LAYER

US20260125810A1US 20260125810 A1US20260125810 A1US 20260125810A1US-20260125810-A1

Abstract

The present disclosure relates to a composition that includes a silicon layer having a first surface and a ZnTiN 2 layer having a second surface, where the first surface and the second surface are physically in contact, and the composition is capable of photovoltaic properties when irradiated with light having a wavelength less than 1200 nm.

Inventors

  • Anna Csencsits KUNDMANN
  • Emily Lowell Warren
  • Ann London GREENAWAY

Assignees

  • ALLIANCE FOR SUSTAINABLE ENERGY, LLC

Dates

Publication Date
20260507
Application Date
20251107

Claims (20)

  1. 1 . A composition comprising: a silicon layer having a first surface; and a ZnTiN 2 layer having a second surface, wherein: the first surface and the second surface are physically in contact, and the composition is capable of photovoltaic properties when irradiated with light having a wavelength less than 1200 nm.
  2. 2 . The composition of claim 1 , wherein there is no intervening layer between the first surface and the second surface.
  3. 3 . The composition of claim 1 , wherein the silicon layer is p-type.
  4. 4 . The composition of claim 1 , wherein the ZnTiN 2 layer has the characteristics of an n-type material.
  5. 5 . The composition of claim 1 , wherein the ZnTiN 2 layer has a thickness between 10 nm and 1000 nm.
  6. 6 . The composition of claim 1 , wherein the ZnTiN 2 layer has a wurtzite crystal structure.
  7. 7 . The composition of claim 1 , wherein the ZnTiN 2 layer has a ratio of Zn/(Zn+Ti) between 0.4 and 0.55.
  8. 8 . The composition of claim 1 , further comprising an oxide layer, wherein the ZnTiN 2 layer is positioned between the oxide layer and the silicon layer.
  9. 9 . The composition of claim 8 , wherein the oxide layer comprises at least one of a zinc oxide, a titanium oxide, or a combination thereof.
  10. 10 . The composition of claim 9 , wherein the zinc oxide comprises ZnO.
  11. 11 . The composition of claim 9 , wherein the titanium oxide comprises TiO 2 .
  12. 12 . The composition of claim 8 , wherein the oxide layer has a thickness between 5 nm and 1000 nm.
  13. 13 . The composition of claim 8 , wherein the oxide layer has a root-mean-square surface roughness of less than 10 nm.
  14. 14 . A device comprising: a composition comprising: a silicon layer having a first surface; an oxide layer; and a ZnTiN 2 layer having a second surface; and an electrolyte, wherein: the device is at least partially immersed in an electrolyte, and the oxide layer is positioned such that the oxide layer can be irradiated with light.
  15. 15 . The device of claim 14 , further comprising: an anode and a circuit, wherein: the composition is configured to function as a cathode.
  16. 16 . The device of claim 14 , further comprising: an additional layer comprising a III-V alloy having a bandgap between 1.5 eV and 2.0 eV.
  17. 17 . The device of claim 16 , wherein the additional layer comprises at least one of gallium, indium, and at least one of nitrogen, phosphorus, or a combination thereof.
  18. 18 . A method utilizing a device, the method comprising: contacting the device with an electrolyte having a pH between 2 and 12; irradiating the device with light; and generating a photovoltage that is substantially independent of the solution potential of a redox couple in the electrolyte.
  19. 19 . The method of claim 18 , wherein the device is configured as a photocathode for water splitting or CO 2 reduction.
  20. 20 . The method of claim 18 , further comprising maintaining an applied potential between +0.5 V and −0.5 V versus RHE at the working electrode while performing a fuel-forming electrochemical reaction.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS This application claims the benefit of U.S. Provisional Patent Application No. 63/717,440 filed Nov. 7, 2024, the contents of which are incorporated herein by reference in their entirety. CONTRACTUAL ORIGIN This invention was made with government support under Contract No. DE-AC36-08GO28308 awarded by the Department of Energy. The government has certain rights in the invention. BACKGROUND New technologies for providing energy and useful chemicals are needed to improve global energy security and reduce reliance on aging and outdated methods for manufacturing useful fuels and chemicals. Photoelectrochemical (PEC) systems offer one promising route to generate fuels by using solar energy to drive endergonic reactions to form H2 or hydrocarbons from abundant inputs like H2O and CO2. Upon illumination PEC devices must generate electrons and holes, separate them, and collect them at different contacts, thus producing high photocurrent and photovoltage. While charge carriers in PV devices are collected at solid contacts to produce current and voltage in an external circuit, charge carriers in PEC devices are collected at a liquid contact to complete the electrochemical circuit and perform (among others) fuel-forming reactions. PV research and design has benefitted from the design of carrier-selective contacts that allow only electrons or holes to be collected while blocking the other carrier type. Practically, such contacts are realized via band alignment that prevents the transport of a particular carrier type and doping that improves the conductivity of majority carriers. Similar strategies have begun to be adopted in PEC device designs, with benefits for device photovoltage, fill factor, and solar-to-fuel efficiency. As the importance of carrier-selective contacts gains greater recognition in the PEC field, there is also an opportunity for co-designing surface layers that are both carrier-selective and protective. Simultaneously meeting both of these criteria would enable devices with high efficiency while overcoming the longstanding durability challenge for PEC systems. Thus, there remains a need for compositions and methods of making such compositions that can meet these criteria. SUMMARY An aspect of the present disclosure is a composition that includes a silicon layer having a first surface and a ZnTiN2 layer having a second surface, where the first surface and the second surface are physically in contact, and the composition is capable of photovoltaic properties when irradiated with light having a wavelength less than 1200 nm. In some embodiments of the present disclosure, there is no intervening layer between the first surface and the second surface. In some embodiments of the present disclosure, the silicon layer may be p-type. In some embodiments of the present disclosure, the ZnTiN2 layer may have the characteristics of an n-type material. In some embodiments of the present disclosure, the ZnTiN2 layer may have a thickness between 10 nm or 1000 nm. In some embodiments of the present disclosure, the ZnTiN2 layer may have a wurtzite crystal structure. In some embodiments of the present disclosure, the ZnTiN2 layer may have a ratio of Zn/(Zn+Ti) between 0.4 and 0.55 or between 0.48 and 0.52 or between 0.49 and 0.51. In some embodiments of the present disclosure, the composition may further include an oxide layer, where the ZnTiN2 layer is positioned between the oxide layer and the silicon layer. In some embodiments of the present disclosure, the oxide layer may include at least one of a zinc oxide, a titanium oxide, or a combination thereof. In some embodiments of the present disclosure, the zinc oxide may include ZnO. In some embodiments of the present disclosure, titanium oxide may include TiO2. In some embodiments of the present disclosure, the oxide layer may have a thickness between 5 nm and 1000 nm. In some embodiments of the present disclosure, the oxide layer may have a root-mean-square surface roughness of less than 10 nm. An aspect of the present disclosure is a device that includes a composition as described herein and an electrolyte, where the device is at least partially immersed in an electrolyte, and the oxide layer is positioned such that the oxide layer can be irradiated with light. In some embodiments of the present disclosure, a device may further include an anode and a circuit, where the composition is configured to function as a cathode. In some embodiments of the present disclosure, a device may further include an additional layer constructed of a III-V alloy having a bandgap between 1.5 eV and 2.0 eV. In some embodiments of the present disclosure, the additional layer may include at least one of gallium, indium, and at least one of nitrogen, phosphorus, or a combination thereof. An aspect of the present disclosure is a method that utilizes a device as described herein, where the method includes contacting the device with an electrolyte having a