title: Mechanism of carrier accumulation in perovskite thin-absorber solar cells.
abstract: Photovoltaic conversion requires two successive steps: accumulation of a photogenerated charge and charge separation. Determination of how and where charge accumulation is attained and how this accumulation can be identified is mandatory for understanding the performance of a photovoltaic device and for its further optimization. Here we analyse the mechanism of carrier accumulation in lead halide perovskite, CH3NH3PbI3, thin-absorber solar cells by means of impedance spectroscopy. A fingerprint of the charge accumulation in high density of states of the perovskite absorber material has been observed at the capacitance of the samples. This is, as far as we know, the first observation of charge accumulation in light-absorbing material for nanostructured solar cells, indicating that it constitutes a new kind of photovoltaic device, differentiated from sensitized solar cells, which will require its own methods of study, characterization and optimization.
authors.affiliation: School of Chemical Engineering and Department of Energy Science, Sungkyunkwan University, Suwon 440-746, Korea.
authors.forename: Hui-Seon
authors.initials: HS
authors.lastname: Kim
authors.forename: Ivan
authors.initials: I
authors.lastname: Mora-Sero
authors.forename: Victoria
authors.initials: V
authors.lastname: Gonzalez-Pedro
authors.forename: Francisco
authors.initials: F
authors.lastname: Fabregat-Santiago
authors.forename: Emilio J
authors.initials: EJ
authors.lastname: Juarez-Perez
authors.forename: Nam-Gyu
authors.initials: NG
authors.lastname: Park
authors.forename: Juan
authors.initials: J
authors.lastname: Bisquert