Efficient perovskite solar cells processed in supercritical carbon dioxide

Perovskite-based solar cells with high power conversion efficiency were produced by annealing the perovskite layer at low temperature in the presence of supercritical carbon dioxide (scCO(2)). Photovoltaic devices were produced with perovskite layers annealed at either 50 degrees C or 100 degrees C, with and without the assistance of scCO(2). For devices annealed at 50 degrees C, the use of scCO(2) resulted in an 88% increase in the power conversion efficiency (from 9.17% to 17.22%) in comparison to devices annealed without scCO(2). For devices annealed at 100 degrees C the use of scCO(2) resulted in a smaller (3%) improvement in power conversion efficiency (from 16.94% to 17.52%). The quality of the perovskite layer at each condition was analyzed using x-ray diffraction, scanning electron microscopy and optical absorption. It was determined that the improvement in the observed device power conversion efficiency corresponds to an improvement in the quality of the photoactive perovskite layer.