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High carrier mobility along the [111] orientation in Cu2O photoelectrodes.

Published version
Peer-reviewed

Repository DOI


Type

Article

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Abstract

Solar fuels offer a promising approach to provide sustainable fuels by harnessing sunlight1,2. Following a decade of advancement, Cu2O photocathodes are capable of delivering a performance comparable to that of photoelectrodes with established photovoltaic materials3-5. However, considerable bulk charge carrier recombination that is poorly understood still limits further advances in performance6. Here we demonstrate performance of Cu2O photocathodes beyond the state-of-the-art by exploiting a new conceptual understanding of carrier recombination and transport in single-crystal Cu2O thin films. Using ambient liquid-phase epitaxy, we present a new method to grow single-crystal Cu2O samples with three crystal orientations. Broadband femtosecond transient reflection spectroscopy measurements were used to quantify anisotropic optoelectronic properties, through which the carrier mobility along the [111] direction was found to be an order of magnitude higher than those along other orientations. Driven by these findings, we developed a polycrystalline Cu2O photocathode with an extraordinarily pure (111) orientation and (111) terminating facets using a simple and low-cost method, which delivers 7 mA cm-2 current density (more than 70% improvement compared to that of state-of-the-art electrodeposited devices) at 0.5 V versus a reversible hydrogen electrode under air mass 1.5 G illumination, and stable operation over at least 120 h.

Description

Keywords

Copper, Electrodes, Solar Energy, Crystallization

Journal Title

Nature

Conference Name

Journal ISSN

0028-0836
1476-4687

Volume Title

Publisher

Springer Science and Business Media LLC
Sponsorship
European Research Council (756962)

Version History

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2*
2024-04-25 09:01:52
Published version added
2024-04-25 09:01:15
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