Photocurrent mapping, also known as a laser beam induced current (LBIC) measurement, provides a spatially resolved, quantitative image of the photocurrent a photovoltaic device produces under illumination. It provides an easily interpretable map of active area performance, which is far more insightful than a single overall PCE efficiency value.
Typically this type of measurement is used for scientific studies at the micrometer scale or the mapping of smaller samples. The average scan times, which can easily stretch into hours for a single, postcard-sized sample, usually do not allow the study of a larger number of samples.
This photocurrent mapping system allows scanning even large samples in a matter of seconds, either in the stationary, desktop versions or even directly inline as part of a roll-to-roll setup. The illumination wavelength can be easily tailored to customer requirements and extended to multiple wavelengths for spatially resolved EQE measurements.
Evaluation of printing defects, studying degradation
The ability to map large areas or an entire sample batch within a practical timeframe is an immensely powerful tool to optimise the manufacturing process and gain statistical leverage. Does a visibly noticeable print defect, e.g. a dust particle or dewetting, have an impact on cell performance? Are print defects located at specific locations? Are serial or parallel connected sub-sections performing equally or are shorts present? Where does long-term degradation occur? This system helps to answer these questions in a rapid manner.
The following two scanning ranges are offered as a standard, while larger scan areas or higher resolution can be catered for on request:
- 28 x 28 mm at 300 µm pixel resolution (scan time < 5s)
- 100 x 150 mm at 500 µm pixel resolution (scan time < 60s)
The smaller scan range version is designed with the typical spin coated sample size in mind, while the postcard sized scan range can accommodate larger samples created on larger, often flexible substrates.
Due to the rapid scan rate, this system can also be operated inline in a roll-to-roll process with scan widths up to 250 mm at web speeds up to 5m/min. Its data acquisition is fully integrated with the roll-to-roll control and barcode labelling system, allowing instant feedback on the current coating conditions or more detailed data analysis at a later point.