The spatial collection efficiency of photovoltaic and photoelectrochemical devices has critical influence on their performance. Defined as the fraction of photogenerated charge carriers created at a specific point within the device that eventually contribute to the collected photocurrent, measurement of the spatial collection efficiency would help to extract the diffusion length of charge carriers and may shed new light on different charge transport mechanisms. We present a non-destructive empirical method to extract the spatial collection efficiency out of Incident Photons to Current Efficiency (IPCE) measurements. Equipped with knowledge on the optics of the system, which can be accurately measured and modeled, the spatial collection efficiency can be extracted from IPCE measurements with high spatial resolution and without a priori assumptions on the charge transport mechanism. In this contribution, we demonstrate the method by extracting the spatial collection efficiency profiles of amorphous silicon solar (PV) cells and thin film hematite photoanodes for solar water splitting. The method is validated theoretically by modeling amorphous silicon solar cells where the spatial collection efficiency is calculated directly and extracted from simulated IPCE measurements. Next, the spatial collection efficiency profiles of thin film hematite photoanodes are extracted out of IPCE measurements at several bias potentials, giving new insights on the photoanodes performance. The relative simplicity of the method along with its applicability to probe in operando performance make this method an important tool for analysis and design of new photovoltaic and photoelectrochemical devices.

Empirical extraction of the spatial collection efficiency of photovoltaic and photoelectrochemical devices

253rd National Meeting (2017)

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