Here, we successfully used a pure layer of [SiW11 O39 ]8- polyoxomethalate (POM) structure as a thin-film scaffold layer for CH3 NH3 PbI3 -based perovskite solar cells (PSCs). A smooth nanoporous surface of POM causes outstanding improvement of the photocurrent density, external quantum efficiency (EQE), and overall efficiency of the PSCs compared to mesoporous TiO2 (mp-TiO2 ) as scaffold layer. Average power conversion efficiency (PCE) values of 15.5 % with the champion device showing 16.3 % could be achieved by using POM and a sequential deposition method with the perovskite layer. Furthermore, modified and defect-free POM/perovskite interface led to elimination of the anomalous hysteresis in the current-voltage curves. The open-circuit voltage decay study shows promising decrease of the electron recombination in the POM-based PSCs, which is also related to the modification of the POM/ perovskite interface and higher electron transport inside the POM layer.
Keywords: keggin type; lead halide; perovskite solar cell; polyoxometalate; scaffold layer.
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