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Title: Femtosecond time-resolved two-photon photoemission studies of ultrafast carrier relaxation in Cu2O photoelectrodes

Journal Article · · Nature Communications

Abstract Cuprous oxide (Cu 2 O) is a promising material for solar-driven water splitting to produce hydrogen. However, the relatively small accessible photovoltage limits the development of efficient Cu 2 O based photocathodes. Here, femtosecond time-resolved two-photon photoemission spectroscopy has been used to probe the electronic structure and dynamics of photoexcited charge carriers at the Cu 2 O surface as well as the interface between Cu 2 O and a platinum (Pt) adlayer. By referencing ultrafast energy-resolved surface sensitive spectroscopy to bulk data we identify the full bulk to surface transport dynamics for excited electrons rapidly localized within an intrinsic deep continuous defect band ranging from the whole crystal volume to the surface. No evidence of bulk electrons reaching the surface at the conduction band level is found resulting into a substantial loss of their energy through ultrafast trapping. Our results uncover main factors limiting the energy conversion processes in Cu 2 O and provide guidance for future material development.

Sponsoring Organization:
USDOE
Grant/Contract Number:
NONE; SC0004993
OSTI ID:
1619475
Journal Information:
Nature Communications, Journal Name: Nature Communications Journal Issue: 1 Vol. 10; ISSN 2041-1723
Publisher:
Nature Publishing GroupCopyright Statement
Country of Publication:
United Kingdom
Language:
English

References (50)

Atomic Layer Deposited Gallium Oxide Buffer Layer Enables 1.2 V Open-Circuit Voltage in Cuprous Oxide Solar Cells journal May 2014
Extended Light Harvesting with Dual Cu 2 O-Based Photocathodes for High Efficiency Water Splitting journal December 2017
Forming Buried Junctions to Enhance the Photovoltage Generated by Cuprous Oxide in Aqueous Solutions journal October 2014
Efficient Water-Splitting Device Based on a Bismuth Vanadate Photoanode and Thin-Film Silicon Solar Cells journal August 2014
Near infrared optical and photoelectric properties of Cu2O. III. Interpretation of experimental results journal June 1972
Binary copper oxide semiconductors: From materials towards devices journal June 2012
Electronic structure and electron dynamics at Si(100) journal February 2005
Photocatalytic Water-Splitting Reaction from Catalytic and Kinetic Perspectives journal October 2014
On the band structure and the absorption spectrum of Cu2O journal July 1966
Experimental and theoretical studies of Cu2O solar cells journal December 1982
Over 18% solar energy conversion to generation of hydrogen fuel; theory and experiment for efficient solar water splitting journal July 2001
Attenuation and escape depths of low-energy electron emission journal July 2001
Carrier dynamics on surfaces studied by two-photon photoemission journal November 2005
Photovoltaic and Photoelectrochemical Solar Energy Conversion with Cu 2 O journal November 2015
Competition Between Hot-Electron Cooling and Large Polaron Screening in CsPbBr 3 Perovskite Single Crystals journal December 2017
Cu 2 O Nanowire Photocathodes for Efficient and Durable Solar Water Splitting journal February 2016
Band Alignment Engineering at Cu 2 O/ZnO Heterointerfaces journal August 2016
Excitonic Effects in Emerging Photovoltaic Materials: A Case Study in Cu 2 O journal January 2017
Monolithic Photoelectrochemical Device for Direct Water Splitting with 19% Efficiency journal June 2018
Femtosecond Studies of Electron Dynamics at Interfaces journal February 2000
Persistent Energetic Electrons in Methylammonium Lead Iodide Perovskite Thin Films journal November 2016
Synthesis and Characterization of High-Photoactivity Electrodeposited Cu 2 O Solar Absorber by Photoelectrochemistry and Ultrafast Spectroscopy journal March 2012
Single-crystal growth and characterization of Cu2O and CuO journal July 1998
Unassisted photoelectrochemical water splitting exceeding 7% solar-to-hydrogen conversion efficiency using photon recycling journal June 2016
Solar water splitting by photovoltaic-electrolysis with a solar-to-hydrogen efficiency over 30% journal October 2016
Hetero-type dual photoanodes for unbiased solar water splitting with extended light harvesting journal December 2016
Hydrogen evolution from a copper(I) oxide photocathode coated with an amorphous molybdenum sulphide catalyst journal January 2014
Efficient direct solar-to-hydrogen conversion by in situ interface transformation of a tandem structure journal September 2015
Highly active oxide photocathode for photoelectrochemical water reduction journal May 2011
Charge separation via asymmetric illumination in photocatalytic Cu2O particles journal July 2018
Boosting the performance of Cu2O photocathodes for unassisted solar water splitting devices journal May 2018
Platinum decorated hierarchical top-porous/bottom-tubular TiO 2 arrays for enhanced gas phase photocatalytic activity journal January 2014
Positive onset potential and stability of Cu 2 O-based photocathodes in water splitting by atomic layer deposition of a Ga 2 O 3 buffer layer journal January 2015
Towards efficient time-resolved X-ray absorption studies of electron dynamics at photocatalytic interfaces journal January 2016
Effects of the preparation method of the ternary CdS/TiO2/Pt hybrid photocatalysts on visible light-induced hydrogen production journal January 2008
820 mV open-circuit voltages from Cu2O/CH3CN junctions journal January 2011
Synthesis and deposition of ultrafine Pt nanoparticles within high aspect ratio TiO2 nanotube arrays: application to the photocatalytic reduction of carbon dioxide journal January 2011
Semiconductor-based nanocomposites for photocatalytic H2 production and CO2 conversion journal January 2013
Low-energy electron inelastic mean free path in materials journal April 2016
Photoelectron transport in the surface region of solids: universal analytical formalism for quantitative applications of electron spectroscopies journal January 2015
Energy-resolved electron spin dynamics at surfaces of p -doped GaAs journal February 2006
Escape dynamics of photoexcited electrons at catechol: TiO 2 ( 110 ) journal July 2006
Atomic resolution mapping of the excited-state electronic structure of Cu 2 O with time-resolved x-ray absorption spectroscopy journal September 2009
Polarization dependence and surface sensitivity of linear and nonlinear photoemission from Bi/Cu(111) journal September 2012
Time-resolved photoemission spectroscopy of electronic cooling and localization in CH 3 NH 3 PbI 3 crystals journal September 2017
Research opportunities to advance solar energy utilization journal January 2016
Detailed Examination of Relaxation Processes of Excitons in Photoluminescence Spectra of Cu 2 O journal July 1997
Electron Trapping in Single Crystal Cuprous Oxide journal January 1972
Perspectives on the photoelectrochemical storage of solar energy journal January 2017
The Effect of Platinum Deposition on the Water Photo-Reduction at p-Cu2O Semiconductor Electrodes with Visible Light Irradiation journal January 2011