Lead Iodide Perovskite Sensitized All-Solid-State Submicron Thin Film Mesoscopic Solar Cell with Efficiency Exceeding 9%

Hui-Seon Kim1, Chang-Ryul Lee1, Jeong-Hyeok Im1, Ki-Beom Lee1, Thomas Moehl2, Arianna Marchioro2,
Soo-Jin Moon2, Robin Humphry-Baker2, Jun-Ho Yum2, Jacques E. Moser2, Michael Gra¨tzel2
& Nam-Gyu Park1
1School of Chemical Engineering and Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea,
2Laboratory for Photonics and Interfaces, Institute of Chemical Sciences and Engineering, School of Basic Sciences, Ecole
Polytechnique Fe´de´rale de Lausanne, CH-1015 Lausanne, Switzerland.

SCIENTIFIC REPORTS | 2 : 591 | DOI: 10.1038/srep00591

We report on solid-state mesoscopic heterojunction solar cells employing nanoparticles (NPs) of methyl ammonium lead iodide (CH3NH3)PbI3 as light harvesters. The perovskite NPs were produced by reaction of methylammonium iodide with PbI2 and deposited onto a submicron-thick mesoscopic TiO2 film, whose pores were infiltrated with the hole-conductor spiro-MeOTAD. Illumination with standard AM-1.5 sunlight generated large photocurrents (JSC) exceeding 17 mA/cm2, an open circuit photovoltage (VOC) of 0.888 V and a fill factor (FF) of 0.62 yielding a power conversion efficiency (PCE) of 9.7%, the highest reported to date for such cells. Femto second laser studies combined with photo-induced absorption measurements showed charge separation to proceed via hole injection from the excited (CH3NH3)PbI3 NPs into the spiro-MeOTAD followed by electron transfer to the mesoscopic TiO2 film. The use of a solid hole conductor dramatically improved the device stability compared to (CH3NH3)PbI3 -sensitized liquid junction cells.