title: Recombination reduction on lead halide perovskite solar cells based on low temperature synthesized hierarchical TiO₂ nanorods.
abstract: Intensive research on the electron transport material (ETM) has been pursued to improve the efficiency of perovskite solar cells (PSCs) and decrease their cost. More importantly, the role of the ETM layer is not yet fully understood, and research on new device architectures is still needed. Here, we report the use of three-dimensional (3D) TiO2 with a hierarchical architecture based on rutile nanorods (NR) as photoanode material for PSCs. The proposed hierarchical nanorod (HNR) films were synthesized by a two-step low temperature (180 °C) hydrothermal method, and consist of TiO2 nanorod trunks with optimal lengths of 540 nm and TiO2 nanobranches with lengths of 45 nm. Different device configurations were fabricated with TiO2 structures (compact layer, NR and HNR) and CH3NH3PbI3, using different synthetic routes, as the active material. PSCs based on HNR-CH3NH3PbI3 achieved the highest power conversion efficiency compared to PSCs with other TiO2 structures. This result can be ascribed mainly to lower charge recombination as determined by impedance spectroscopy. Furthermore, we have observed that the CH3NH3PbI3 perovskite deposited by the two-step route shows higher efficiency, surface coverage and infiltration within the structure of 3D HNR than the one-step CH3NH3PbI(3-x)Cl(x) perovskite.
authors.affiliation: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain. sero@uji.es and Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Apartado Postal 34, Temixco, Mor., México 62580. merg@ier.unam.mx.
authors.forename: Oscar A
authors.initials: OA
authors.lastname: Jaramillo-Quintero
authors.affiliation: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain. sero@uji.es.
authors.forename: Mauricio
authors.initials: M
authors.lastname: Solís de la Fuente
authors.affiliation: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain. sero@uji.es.
authors.forename: Rafael S
authors.initials: RS
authors.lastname: Sanchez
authors.affiliation: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain. sero@uji.es.
authors.forename: Ileana B
authors.initials: IB
authors.lastname: Recalde
authors.affiliation: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain. sero@uji.es.
authors.forename: Emilio J
authors.initials: EJ
authors.lastname: Juarez-Perez
authors.affiliation: Instituto de Energías Renovables, Universidad Nacional Autónoma de México, Apartado Postal 34, Temixco, Mor., México 62580. merg@ier.unam.mx.
authors.forename: Marina E
authors.initials: ME
authors.lastname: Rincón
authors.affiliation: Institute of Advanced Materials (INAM), Universitat Jaume I, 12006 Castelló, Spain. sero@uji.es.
authors.forename: Iván
authors.initials: I
authors.lastname: Mora-Seró