title: Mechanism of Charge Transfer and Recombination Dynamics in Organo Metal Halide Perovskites and Organic Electrodes, PCBM, and Spiro-OMeTAD: Role of Dark Carriers.
abstract: Despite the unprecedented interest in organic-inorganic metal halide perovskite solar cells, quantitative information on the charge transfer dynamics into selective electrodes is still lacking. In this paper, we report the time scales and mechanisms of electron and hole injection and recombination dynamics at organic PCBM and Spiro-OMeTAD electrode interfaces. On the one hand, hole transfer is complete on the subpicosecond time scale in MAPbI3/Spiro-OMeTAD, and its recombination rate is similar to that in neat MAPbI3. This was found to be due to a high concentration of dark charges, i.e., holes brought about by unintentional p-type doping of MAPbI3. Hence, the total concentration of holes in the perovskite is hardly affected by optical excitation, which manifested as similar decay kinetics. On the other hand, the decay of the photoinduced conductivity in MAPbI3/PCBM is on the time scale of hundreds of picoseconds to several nanoseconds, due to electron injection into PCBM and electron-hole recombination at the interface occurring at similar rates. These results highlight the importance of understanding the role of dark carriers in deconvoluting the complex photophysical processes in these materials. Moreover, optimizing the preparation processes wherein undesired doping is minimized could prompt the use of organic molecules as a more viable electrode substitute for perovskite solar cell devices.
authors.affiliation: Division of Chemical Physics, Lund University , Box 124, 221 00 Lund, Sweden.
authors.forename: Carlito S
authors.initials: CS
authors.lastname: Ponseca
authors.affiliation: Department of Chemical Engineering, Delft University of Technology , 2628 BL Delft, The Netherlands.
authors.forename: Eline M
authors.initials: EM
authors.lastname: Hutter
authors.affiliation: Departamento de Quimica Fisica, Facultad de Ciencias Ambientales y Bioquimica, and INAMOL, Universidad de Castilla-La Mancha , Avenida Carlos III, S/N, 45071 Toledo, Spain.
authors.forename: Piotr
authors.initials: P
authors.lastname: Piatkowski
authors.affiliation: Departamento de Quimica Fisica, Facultad de Ciencias Ambientales y Bioquimica, and INAMOL, Universidad de Castilla-La Mancha , Avenida Carlos III, S/N, 45071 Toledo, Spain.
authors.forename: Boiko
authors.initials: B
authors.lastname: Cohen
authors.affiliation: Division of Chemical Physics, Lund University , Box 124, 221 00 Lund, Sweden.
authors.forename: Torbjörn
authors.initials: T
authors.lastname: Pascher
authors.affiliation: Departamento de Quimica Fisica, Facultad de Ciencias Ambientales y Bioquimica, and INAMOL, Universidad de Castilla-La Mancha , Avenida Carlos III, S/N, 45071 Toledo, Spain.
authors.forename: Abderrazzak
authors.initials: A
authors.lastname: Douhal
authors.affiliation: Division of Chemical Physics, Lund University , Box 124, 221 00 Lund, Sweden.
authors.forename: Arkady
authors.initials: A
authors.lastname: Yartsev
authors.affiliation: Division of Chemical Physics, Lund University , Box 124, 221 00 Lund, Sweden.
authors.forename: Villy
authors.initials: V
authors.lastname: Sundström
authors.affiliation: Department of Chemical Engineering, Delft University of Technology , 2628 BL Delft, The Netherlands.
authors.forename: Tom J
authors.initials: TJ
authors.lastname: Savenije