Facile scalable synthesis of MoO2 nanoparticles by new solvothermal cracking process and their application to hole transporting layer for CH3NH3PbI3 planar perovskite solar cells

Abstract

∼10nm sized MoO2 nanoparticles with high BET surface area of 170.14m2/g were synthesized via scalable new process of combining the ultrasonic spray pyrolysis and solvothermal cracking process. Initially, we synthesized polycrystalline MoO3 microparticles by the ultrasonic spray pyrolysis at 500°C or 600°C. Then the MoO3 microparticles were disassembled into crystalline grains and the grains were subsequently shattered to small MoO2 nanoparticles through the solvothermal polyol reduction process because the polycrystalline MoO3 microparticles are disassembled by thermal expansion and the crystalline MoO3 grains are shattered by volume shrinkage due to phase transition from MoO3 to MoO2. Finally, we applied the MoO2 nanoparticles/toluene solution to new inorganic hole transporting material for planar CH3NH3PbI3 perovskite solar cells. The planar type CH3NH3PbI3 perovskite solar cells exhibited stable efficiency of 14.8% for forward scan condition and 15.5% for reverse scan condition under illumination of 1 Sun (100mW/cm2).