Incident Photon-to-Current Efficiency and Photocurrent Spectroscopy

The incident photon-to-current efficiency (IPCE) is a measure of the ratio of the photocurrent (converted to an electron transfer rate) versus the rate of incident photons (converted from the calibrated power of a light source) as a function of wavelength. Measuring the IPCE is also useful to determine the band gap. The band gap derived from IPCE may be higher than that obtained by optical spectroscopy techniques. Applied bias IPCE and white light bias IPCE experiments are discussed. Photocurrent spectroscopy examines the photocurrent produced by an electrochemical cell as a function of wavelength of the incident light. The optical bulk band gap of the semiconductor electrode can be determined along with information about whether it is a direct or indirect transition.