Fluorescence spectroscopy-based study of balanced transport of charge carriers in hot-air-annealed perovskites

Abstract

Using fluorescence spectroscopy, we investigate the transport of charge carriers in (p-i-n) planar perovskite (CH3NH3PbI3-xClx) solar cells with the structure ITO/PEDOT:PSS/perovskites/PCBM/Ca/Al, in which the perovskite morphology is optimized by moisture pretreatment (MPT) and the hot-air-annealing process (HAAP). After annealing with hot air, the electron transport time of the perovskites is shortened by a factor of 3.6 (from 28.8 to 7.9 ns), eventually leading to balanced transport of electrons and holes (characterized by the fluorescence-decay time constants of 7.9 and 7.6 ns, respectively). These results are in good agreement with the observed increase in the photovoltaic conversion efficiency. (C) 2018 Elsevier B.V. All rights reserved.