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The Incident Monochromatic Photon-Electron Conversion Efficiency (IPCE) is defined as the ratio of the number of electrons flowing through a closed circuit to the number of incident monochromatic photons, used to evaluate the photoconversion efficiency at different wavelengths. It is one of the important indicators for assessing the photoelectrochemical performance of photoelectrodes.
Since semiconductor materials have different responses to incident light of different wavelengths, measuring the IPCE of a photoelectrode can more accurately evaluate the utilization of monochromatic photons by the photoelectrode, and therefore, it can be more targeted in improving the photoelectrode to enhance its photoelectrochemical performance[1].
The IPCE calculation formula is as follows[2]:
jph: Photocurrent density (mA·cm-2), measured by chronoamperometry (constant potential)
h: Planck's constant (6.62×10-34 J·s)
c: Speed of light (3.0×108 m·s-1)
e: Charge carried by a single electron (1.6×10-19 C)
Pmono: Optical power density of monochromatic light (mW·cm-2)
λ: Monochromatic light wavelength
Simplified, it can be represented as formula (2)[1]:
jp: Photocurrent density (mA·cm-2)
jd: Dark current density (mA·cm-2)
λ: Incident monochromatic light wavelength (nm)
pin: Optical power density received by the photoelectrode (mW·cm-2)
The higher the photocurrent density of the photoelectrode, the higher the IPCE value, which can be further improved by enhancing the charge separation and collection efficiency of the photoelectrode material, thereby increasing the IPCE value.
Perfectlight Science and Technology's PL-PES Spectral Photoelectrochemical System can automatically characterize semiconductor materials' photocurrent, photovoltage, and other photoelectric performance parameters as a function of incident light wavelength in the ultraviolet, visible, and near-infrared wavelength range. It can be used in conjunction with Kelvin probes, conductivity probes, and other testing equipment, and can control output light wavelength, light irradiation time, and synchronize with the electrochemical workstation. PL-PES Spectral Photoelectrochemical System is mainly used for photocurrent testing under different applied voltage conditions, different light wavelengths, different light intensities, and different voltage and light intensity scans, as well as open-circuit potential testing under specific light wavelengths.
Fig.1 a) PL-PES Spectral Photoelectrochemical System; b) IPCE Curve and Photocurrent/Voltage Behavior Spectra
Fig. 2. a) IPCE at 0 V vs. Ag/AgCl[3]; b) IPCE at 1.2 V vs. Ag/AgCl[4]; c) IPCE [5]; d) IPCE at 1.2 VRHE; e) band gaps from photocurrent measurements[6]；f) IPCEs at 0.6 and 1.2 VRHE, respectively[7]
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