Exploring photogenerated charge carrier transfer in semiconductor/metal junctions using Kelvin probe force microscopy

Semiconductor/metal junctions are widely discussed in photocatalysis. However, there is a notable scarcity of systematic studies focusing on photogenerated charge carrier transfer in such junctions. Herein, CdS/Pt, CdS/Au, and CdS/Ag are synthesized to serve as model systems for investigating the charge carrier transfer in semiconductor/metal junctions. Kelvin probe force microscopy is employed to visualize the transfer of photogenerated carriers in these materials. The results show that the electron transfer behavior under illumination is related to the conduction band position of CdS and the Fermi level position of the metal. Moreover, Schottky junctions hinder the transfer of photogenerated electrons from CdS to Pt and Au, whereas ohmic contacts facilitate the transfer of photogenerated electrons from CdS to Ag. This work provides novel insights into the mechanisms governing the transfer of photogenerated carriers in semiconductor/metal junctions.