Chalcopyrite thin film absorbers such as Cu(In,Ga)Se2 (CIGS) exhibit excellent solar energy conversion efficiency, particularly when coupled with CdS to form an excellent p-n junction. An increasing number of investigations have focused on adopting protective layers and cocatalysts for chalcopyrite/CdS to improve its stability and surface reaction kinetics. However, satisfactory performance has yet not been obtained, primarily due to the uncontrollable deposition of surface HER cocatalysts as well as the considerable charge recombination at the interface between CdS and protective layers. Here, we take Cu(In,Ga)Se2/CdS as a prototype and demonstrate a two-step platinization strategy to independently control the size and dispersion of Pt cocatalysts towards faster surface reaction. Moreover, Al2O3 interlayer is adopted to passivate the defects at CdS/TiO2 interface for improved charge transfer. This report represents new insights in controlling surface and interface properties for heterojunction photoelectrodes.
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Energy Environ. Sci. 2018, DOI:10.1039/C7EE03650G