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Use of Masks in Image Processing to Analyze the Local Distribution of the Work Function in Photovoltaic Contacts

In perovskite solar cells, the contact of the perovskite absorber layer to the transport layers plays a crucial role. As an example, the contact of the lead-free Cs2AgBiBr6 double perovskite to the hole transport material pentacene (Pn) was investigated by in-situ growth studies. Morphology and work function were measured by Kelvin probe force microscopy (KPFM) during the stepwise growth of Pn on differently modified Cs2AgBiBr6 by physical vapor deposition. 
The image visualizes the procedure of assigning morphological features of Pn to different contributions to the measured work function. The work function image indicates two distinct regimes of work functions. Therefore, masks were created (1) containing all areas of lower value (red mask) or higher value (blue mask), respectively. Application of these masks to the morphology image (2) revealed a clear correlation of work function and morphology. Clusters of Pn grains present under the red mask exhibit a lower work function compared to the blue mask, characteristic of a Pn layer. This correlation of the images allows to assign (3) contributions of Pn layer and Pn grains to the observed broad distribution of the work function. A uniform work function was established for >50 nm Pn, which was then used to study photovoltaic cells. 

Publication: T.P. Schneider, F. Schmitz, T. Gatti & D. Schlettwein. ACS Appl. Mater. Interfaces 2026, DOI: 10.1021/acsami.5c24299

Dieses Bild wurde eingereicht von Tim Schneider (AG Prof. Schlettwein).

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