Semiconductor interfacial carrier dynamics via photoinduced electric fields

Abstract

Solar photoconversion in semiconductors is driven by charge separation at the interface of the semiconductor and contacting layers. Here we demonstrate that time-resolved photoinduced reflectance from a semiconductor captures interfacial carrier dynamics. We applied this transient photoreflectance method to study charge transfer at p-type gallium-indium phosphide (p-GaInP2) interfaces critically important to solar-driven water splitting. We monitored the formation and decay of transient electric fields that form upon photoexcitation within bare p-GaInP2, p-GaInP2/platinum (Pt), and p-GaInP2/amorphous titania (TiO2) interfaces. The data show that a field at both the p-GaInP2/Pt and p-GaInP2/TiO2 interfaces drives charge separation. Additionally, the charge recombination rate at the p-GaInP2/TiO2 interface is greatly reduced owing to its p-n nature, compared with the Schottky nature of the p-GaInP2/Pt interface.

Photocorrosion-Limited Maximum Efficiency of Solar Photoelectrochemical Water Splitting

“…We revealed that the thermodynamic stability is strongly coupled to the energy position [32,38,40,41].…”

Hybrid Photoelectrochemical Water Splitting Systems: From Interface Design to System Assembly

“…The reactivity was impressive and for p‐Si/TiO 2 / 24 , there was a negligible change in catalytic activity after a 1 h reaction time, indicative of the high durability. In the structure, beside protecting the p‐Si surface, TiO 2 could also act as a functional layer to enhance covalent linking and tailor the p‐Si/electrolyte interfacial energetics by forming a p‐n junction 29,32,33,158. In a very recent experiment, Cadot and co‐workers drop‐casted a Mo 3 S 4 (AsW 12 ) cluster onto the p‐Si surface to form a hybrid photocathode which exhibited improved photocurrent with no decrease in a 40 h PEC reaction period and decreased overpotential by ≈700 mV compared to bare p‐Si 35…”

Energetic Tug‐of‐War between Pt and Leaky TiO2: Positive and Negative Effects on the Function of Molecularly‐Modified p‐Si(111)|TiO2|Pt Photocathodes

“…A similar interfacial architecture based on a bimetallic CuAg CO 2 reduction catalyst on TiO 2 provided the catalytic/protective layer for a p‐type Si photocathode . In addition to improving the durability of the interface, we have developed techniques that quantify the fundamental kinetic and thermodynamic benefits of oxides, catalysts, as well as molecular species at the semiconductor|electrolyte interface …”

“…[22] In addition to improving the durability of the interface, we have developed techniques that quantify the fundamental kinetic and thermodynamic benefits of oxides, catalysts, as well as molecular species at the semiconductor j electrolyte interface. [23][24][25] Kinetically, spatial separation of the photoexcited electrons (in the TiO 2 ) and holes (remaining in the underlying semiconductor) limits recombination. [23] As the underlying semiconductor and protecting oxide are p-and n-type respectively, a p-n junction between the layers enhances the field within the semiconductor, further driving charge separation.…”

“…[23][24][25] Kinetically, spatial separation of the photoexcited electrons (in the TiO 2 ) and holes (remaining in the underlying semiconductor) limits recombination. [23] As the underlying semiconductor and protecting oxide are p-and n-type respectively, a p-n junction between the layers enhances the field within the semiconductor, further driving charge separation. In addition to the conduction band charge transport mechanism, defects within the TiO 2 also play a role.…”