Effect of preheated, delayed annealing process on the ultrafast carriers dynamics of perovskite films using ultrafast absorption spectroscopy

Organic halogenated perovskite material, as an optical material with great development potential, shows excellent application value in the field of solar cells. Solar cells based on organometal halide perovskites possess photoelectricity efficiencies exceeding 25.2%, however, they suffer from oxidization and degradation. In this paper, we present a fabrication technique based on the preheating treatment and delayed annealing to obtain high quality perovskite films. Using the femtosecond transient absorption (TA) spectroscopy, we investigate the transport and lifetime of internal carriers of perovskite films prepared by the preheating treatment and delayed annealing process. The experimental results show that the perovskite film obtained by the preheated treatment is easier to control the carrier recombination rate than the perovskite film obtained by the conventional method. Furthermore, perovskite film with delayed annealing 1 h has a shorter transport time of carriers from the perovskite layer to the hole transport layer, effectively avoiding the direct recombination of carriers. The novel method put forward in this work enables the stabilization and high efficiency of perovskite solar cells.