Combination of high and low temperature carbon pastes to fabricate counter electrode of perovskite solar cell

Abstract

The high cost, complicated synthesis and coating process of organic hole-transporting materials such as Spiro-OMeTAD, as well as their negative effect on the stability of the device, are the principal impediments for the commercialization of perovskite solar cells. To overcome these obstacles, the attentions increased toward developing hole-transporting material-free perovskite solar cells. In the present work, perovskite solar cell was fabricated by combining two kinds of carbon counter electrodes, including one layer of mesoscopic carbon paste mixed with terpineol and covered by one layer of carbon paste mixed in ethyl-acetate. The crucial difference between two layers lies in their sintering temperature. Also, different thicknesses for the first carbon layer, as well as the effect of dipping time in methyl ammonium iodide were examined. Following the photovoltaic characterization, the achieved optimized efficiency of the hole-conductor-free perovskite solar cell was 11.82 ± 2.07%. Besides, the thickness of the carbon, layer that affects the conductivity and fill factor, and the appropriate contact between perovskite and carbon counter electrode are considered here as two important parameters in optimizing the efficiency of hole-conductor-free perovskite solar cell.