The Incident Monochromatic Photon-Electron Conversion Efficiency (IPCE) is defined as the ratio of the number of electrons passing through a closed circuit to the number of photoelectrons of incident monochromatic light. It is used to evaluate the photoelectric conversion efficiency at different wavelengths and is one of the important indicators for assessing the photoelectrochemical performance of photoelectrodes.
Due to the varying responses of semiconductor materials to light of different wavelengths, measuring the IPCE of a photoelectrode provides a more accurate assessment of the utilization of monochromatic light photons by the photoelectrode. This, in turn, makes the improvement of photoelectrodes more targeted in enhancing their photoelectrochemical performance[1].
IPCE Calculation Formula is provided below[2]:
jph: Photocurrent density (mA·cm-2), measured using the time-current method (constant potential)
h: Planck's constant (6.62×10-34 J·s)
c: Speed of light (3.0×108 m·s-1)
e: Charge of a single electron (1.6×10-19 C)
Pmono: Power density of monochromatic light (mW·cm-2)
λ: Wavelength of monochromatic light
The simplified form is represented as equation (2)[1]:
jp: Photocurrent density (mA·cm-2)
jd: Dark current density (mA·cm-2)
λ: Wavelength of incident monochromatic light (nm)
pin: Power density of incident light on the photoelectrode (mW·cm-2)
The larger the photocurrent density of the photoelectrode, the higher the IPCE value. This can be achieved by improving the charge separation and collection efficiency of the photoelectrode material, thereby further enhancing the photocurrent density and increasing the IPCE value.
Perfectlight's PL-PES Spectral Photoelectrochemical System can automatically characterize and measure the photoelectric performance parameters such as photocurrent and photovoltaic properties of semiconductor materials as a function of the incident light's wavelength in the ultraviolet, visible, and near-infrared wavelength ranges. It can be used in conjunction with equipment like Kelvin probes and conductivity probes, allowing control over output light wavelength, exposure time, and synchronization with electrochemical workstations. The 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 Spectrum
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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