The Photoelectrochemical Kinetics of p‐Type GaP

Abstract

Current voltage curves have been measured for the reduction of H+, Fe(III), and methylviologen at illuminated p‐type normalGaP . The mechanisms and kinetic pathways for the reactions have been elucidated using the ring‐disk electrode where the ring electrode measures the fluxes of the Faradaic products from the disk. Faster processes involving surface intermediates have been followed by measuring the transient currents on switching the light on or off and by modulating the light source. The variation of the different Faradaic photocurrents with potential, with irradiance, and with rotation speed are quantitatively explained by a model in which photogenerated electrons diffuse to the surface of the semiconductor and there undergo competitive reactions with H+, Fe(III), or surface states.

Modeling of Electrical Transients in the Semiconductor/Electrolyte Cell for Photogeneration of Charge Carriers in the Bulk

“…It has often been observed in cyclic voltammetry experiments, where the sample was illuminated with chopped light during the scan. [20][21][22][23] Since a comparable behavior has not been reported for solid state photovoltaic cells, the question arises whether the decay of the initial photocurrent is an intrinsic property of the semiconductor-electrolyte interface, most likely due to the fairly long lifetime of the charge carriers at the crystal surface. To our knowledge Peter 24 was the first in suggesting a model that could explain the time-dependent decay of photocurrent transients as in Figure 4.…”

Modulated Light Studies of the Electrochemistry of Semiconductors: Theory and Experiment

“…We (1) and others (2)(3)(4)(5) have also shown how redox kinetics at this overlayer plays a crucial role in the solar-conversion efficiency of devices based on this "heterojunction-photoelectrode" concept. We (1) and others (2)(3)(4)(5) have also shown how redox kinetics at this overlayer plays a crucial role in the solar-conversion efficiency of devices based on this "heterojunction-photoelectrode" concept.…”

“…For the distribution exp (-x2), we write AG* = AG* -"txRT [2] and in (k) = in (k) + -/x [3] where we have introduced the useful parameter ~ which describes the dispersion (6). For the distribution exp (-x2), we write AG* = AG* -"txRT [2] and in (k) = in (k) + -/x [3] where we have introduced the useful parameter ~ which describes the dispersion (6).…”

Photoelectrochemical Investigations of Semiconductor Nanoparticles and Their Application to Solar Cells

“…112,113 The modulation frequency is usually varied in the range from a few tens of kilohertz down to 0.1 Hz. Common light sources employed for IMPS experiments include LEDs, continuous lasers modulated by acousto-optic devices, and diode lasers, 114,115 but other DC-driven light sources such as arc lamps 116,117 can also be used. A typical setup for IMPS experiments is shown in Figure 8.…”

“…The ac light intensity is chosen to be sufficiently small (typically 10% or less of the DC light intensity) to guarantee a linear response of the system under investigation. , The modulation frequency is usually varied in the range from a few tens of kilohertz down to 0.1 Hz. Common light sources employed for IMPS experiments include LEDs, continuous lasers modulated by acousto-optic devices, and diode lasers, , but other DC-driven light sources such as arc lamps , can also be used. A typical setup for IMPS experiments is shown in Figure .…”