Highly efficient inverted poly(3-hexylthiophene): Methano-fullerene [6,6]-phenyl C71-butyric acid methyl ester bulk heterojunction solar cell with Cs2CO3 and MoO3

We have studied the fabrication of an inverted P3HT:PC71BM bulk hetero-junction (IBHJ) solar cell using ultrathin cesium carbonate (Cs2CO3) and molybdenum trioxide (MoO3) as the cathodic and anodic buffer layers, respectively. The influence of MoO3 thickness on the performance of the IBHJ solar cells was investigated for thicknesses ranging from 0.75 to 3 nm and the optimum thickness was found to be 2 nm, which showed the highest power conversion efficiency of 4.01%. We also found that the power conversion efficiency of the IBHJ solar cells is relatively retained even in low temperature while that of BHJ solar cell rapidly decreased with decreasing temperature and the stability in air is also much better.

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► An new Inverted bulk hetero-junction (BHJ) solar cells with Cs2CO3 and MoO3 layers.
► The optimized thickness of MoO3 is ∼2 nm.
► The IBHJ solar cell shows good environmental stability.
► Power conversion efficiency of the IBHJ solar cell is retained even in low temperatures.