Illuminated Lock-In Thermography Decomposition: Identification of Power Contributions

In this paper, we introduce a novel method for decomposing Illuminated Lock-In Thermography (ILIT) measurements into spatially resolved and physically meaningful components. These components represent the power dissipation in individual elements of an equivalent circuit model for solar cells. The decomposition process combines a series of differential ILIT images, acquired at various bias points, with a fitted equivalent circuit model derived from the device’s IV characteristics. By correlating the amplitudes of the ILIT images with the corresponding total differential power dissipation predicted by the circuit model, we achieve a linear decomposition of distinct power contributions. This approach identifies a spatial distribution of power dissipation associated with each element in the equivalent circuit. We present the theoretical foundation of our method and demonstrate its application to a silicon heterojunction solar cell. Our results show that ILIT images can be decomposed into components corresponding to the elements in the circuit model, providing a detailed visualization of the spatial distribution of various power contributions.