Solution processed n-type mixed metal oxide layer for electron extraction in inverted polymer solar cells

•A solution-processed n-type mixed metal oxide layer of ZnO:Cs2CO3 for inverted polymer solar cells.•The optimized polymer solar cell shows power conversion efficiency as high as 5.29%.•XPS and AFM confirm the composition and surface morphology of n-type mixed electron extraction layer.

In this paper we demonstrate an efficient inverted polymer bulk heterojunction (BHJ) solar cells using solution processed interfacial layer by mixing zinc oxide (ZnO) with cesium carbonate (Cs2CO3) for ideal electron extraction and transport. The optimized inverted BHJ solar cell with n-type mixed (ZnO:Cs2CO3) electron transport layer and blend of poly (3-hexylthiophene):Indene-C60 bisadduct as a photoactive layer shows a power conversion efficiency as high as 5.29%. This performance enhancement is attributed to improved interfacial contact between photoactive layer and electron extraction layer, low leakage current, and a suitable surface morphology for electron extraction and transport.

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