Enhancing Photovoltage of Silicon Photoanodes by a High Work-function Coordination Polymer

25 May 2022, Version 1
This content is a preprint and has not undergone peer review at the time of posting.

Abstract

A metal-insulator-semiconductor (MIS) structure based on an inhomogeneous junction has been recently proven to be highly efficient at photoelectrochemical (PEC) water oxidation. Engineering the surrounding layer of the MIS nanojunction is crucial to maximize the photovoltage. Specifically, for an n-type photoanode, a high work-function material is desired to create a large Schottky barrier that assists the hole transfer to oxidize water while blocking the electron transfer. We demonstrate the use of copper(I) thiocyanate (CuSCN), a transparent p-type coordination polymer semiconductor with a high work function, to surround the n-Si/SiOx/Cu nanojunctions, resulting in an increased effective barrier height from 0.71 to 1.03 eV. This phenomenon, known as the pinch-off effect, is also applied to improve the performance of the planar n-Si/SiOx/Cu electrode via a PEC dissolution method that creates an inhomogeneous surface covered with CuOx. The Cu/CuSCN nanojunction still shows superior performance due to the favorable energetics of CuSCN.

Keywords

Photoelectrochemical water splitting
Silicon photoanodes
Metal-semiconductor-insulator junctions
Copper(I) thiocyanate
Photovoltage

Supplementary materials

Title
Description
Actions
Title
Supporting information
Description
Note S1: Experimental methods; Note S2: Verifying the formation of CuSCN layer; Note S3: Stability of Cu-modified Si photoanodes; Note S4: XPS characterization of as-sputtered and photodissoluted Cu; additional PEC characterizations; XPS spectra; Raman spectra; UV-Vis reflectance spectra; SEM images; OCP measurements; Kelvin probe measurements; photoelectron yield spectrum of the Au reference.
Actions

Comments

Comments are not moderated before they are posted, but they can be removed by the site moderators if they are found to be in contravention of our Commenting Policy [opens in a new tab] - please read this policy before you post. Comments should be used for scholarly discussion of the content in question. You can find more information about how to use the commenting feature here [opens in a new tab] .
This site is protected by reCAPTCHA and the Google Privacy Policy [opens in a new tab] and Terms of Service [opens in a new tab] apply.