On the application of the vibrating Kelvin probe method for quality control of Cu(In,Ga)(Se,S)₂ thin‐film solar modules

Abstract

In this contribution, the application possibilities of Kelvin probe mapping on Cu(In,Ga)(Se,S) 2 thin-film modules was explored and compared with dark lock-in thermography and electroluminescence imaging techniques. It has been shown that unlike any imaging technique, Kelvin probe measurements are able to detect spatial potential variations in both reverse and forward biases applied to a module and therefore to localize electrical defects and material inhomogeneities of a module, which are not visible to other characterization techniques. Moreover, Kelvin probe measurements under reverse bias conditions demonstrated a high sensitivity to variations of the reverse currents of the single diodes connected in series even under conditions where open-circuit voltage is not severely affected by inhomogeneities. Therefore, this mapping technique can be a valuable tool in a quality assessment process especially as an early warning tool in production.

BME VIK Annual Research Report on Electrical Engineering and Computer Science 2016

“…The high resolution (100 um) surface potential maps were acquired under illuminated and dark conditions, thus a surface photovoltage map could also be derived. The measurement method was able to detect invisible shunts and short-circuited cells, thus giving a contactless detection possibility for such defects [46]. Results were verified by photoluminescence and dark lock in thermography measurements.…”