Abstract
Here, unbiased water splitting with 2% solar-to-hydrogen efficiency under AM 1.5 G illumination using new materials based on GaSb0.03P0.97 alloy is reported. Freestanding GaSbxP1− x is grown using halide vapor phase epitaxy. The native conductivity type of the alloy is modified by silicon doping, resulting in an open-circuit potential (OCP) of 750 mV, photocurrents of 7 mA cm−2 at 10 sun illumination, and corrosion resistance in an aqueous acidic environment. Alloying GaP with Sb at 3 at% improves the absorption of high-energy photons above 2.68 eV compared to pure GaP material. Electrochemical Impedance Spectroscopy and illuminated OCP measurements show that the conduction band of GaSbxP1− x is at −0.55 V versus RHE irrespective of the Sb concentration, while photocurrent spectroscopy indicates that only radiation with photon energies greater than 2.68 eV generate mobile and extractable charges, thus suggesting that the higher-laying conduction bands in the Γ 1 valley of the alloys are responsible for exciton generation.
Original language | American English |
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Article number | 1703247 |
Number of pages | 9 |
Journal | Advanced Energy Materials |
Volume | 8 |
Issue number | 16 |
DOIs | |
State | Published - 2018 |
Bibliographical note
Publisher Copyright:© 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
NREL Publication Number
- NREL/JA-5900-70812
Keywords
- bandgap tuning
- DFT calculations
- HVPE
- III–V alloy
- water splitting