Acetylacetone Improves the Performance of Mixed Halide Perovskite Solar Cells

In this contribution, we show CH3NH3PbI3-xClx perovskite solar cells (PSCs) processed in ambient air from a solution containing the diketone, acetylacetone (AA) solvent as an additive. PSCs with the AA additive show enhanced photovoltaic properties. The optimized PSC with 10 vol % AA additive shows an average open-circuit voltage (V-OC) of about 1.02 V, short-circuit current density (J(sc)) of around 18.7 mA/cm(2), fill factor of about 76%, and power conversion efficiency of around 14.5%. Atomic force microscopy topographic imaging depicts that the addition of AA into the MAPbI(3-x)Cl(x) solution enhances the crystal growth with comparable improvement in the surface smoothness. Electrochemical impedance spectroscopy and intensity modulated photovoltage spectroscopy investigations show that incorporation of AA resulted in the improvement of charge carrier dynamics in the bulk and across interfaces, and reduction of recombination pathways. Moreover, MAPbI(3-x)Cl(x) films with the AA additive exhibit stronger photoluminescence compared to the pristine MAPbI(3-x)Cl(x) films. This appears to confirm that the AA solvent additive plays a vital role to reduce the trap states and recombination conduits across the film, which boosts the enhancement of radiative recombination pathways. We believe that this additive is highly practical and a viable option to fabricate and optimize large-area, stable, thin film PSCs in ambient environment.