Letter pubs.acs.org/JPCL
Unraveling Charge Carriers Generation, Diffusion, and Recombination in Formamidinium Lead Triiodide Perovskite Polycrystalline Thin Film Piotr Piatkowski,† Boiko Cohen,† Carlito S. Ponseca, Jr.,‡ Manuel Salado,§ Samrana Kazim,§ Shahzada Ahmad,§ Villy Sundström,‡ and Abderrazzak Douhal*,† †
J. Phys. Chem. Lett. 2016.7:204-210. Downloaded from pubs.acs.org by DURHAM UNIV on 01/02/19. For personal use only.
Departamento de Química Física, Facultad de Ciencias Ambientales y Bioquímica, and INAMOL, Universidad de Castilla-La Mancha, Avenida Carlos III, Sin Número, 45071 Toledo, Spain ‡ Division of Chemical Physics, Lund University, Box 124, 22100 Lund, Sweden § Abengoa Research, Abengoa, Campus Palmas Altas, C/Energia Solar, 41014 Sevilla, Spain S Supporting Information *
ABSTRACT: We report on studies of the formamidinium lead triiodide (FAPbI3) perovskite film using time-resolved terahertz (THz) spectroscopy (TRTS) and flash photolysis to explore charge carriers generation, migration, and recombination. The TRTS results show that upon femtosecond excitation above the absorption edge, the initial high photoconductivity (∼75 cm2 V−1 s−1) remains constant at least up to 8 ns, which corresponds to a diffusion length of 25 μm. Pumping below the absorption edge results in a mobility of 40 cm2 V−1 s−1 suggesting lower mobility of charge carriers located at the bottom of the conduction band or shallow sub-bandgap states. Furthermore, analysis of the THz kinetics reveals rising components of
