Figure 3.

Push-only (pump beam blocked) photoconductivity transients for a FA_0.83Cs_0.17SnI₃ thin film with high hole doping (no tin fluoride additive). Presented transients were induced by sub-bandgap photoexcitation centered at 1390 nm wavelength with excitation fluences indicated in the legend. The relative change in THz field transmission (−ΔT/(T + ΔT)) is proportional to the change in conductivity of the thin film. The empty hoops represent the measured photoconductivity data, and the solid lines show fits of a monoexponential decay convoluted with Gaussian broadening. The standard deviation of the Gaussian (representing system resolution) was determined as s = 200 fs, as described in Section VI of the Supporting Information. The fit to the highest fluence data yields a decay time of τ = 357 fs ±10 fs for the relaxation process. This decay lifetime is then fixed for fitting lower fluence transients due to the lack of decay dynamics dependence on the push fluence demonstrated in Figure S3A in the Supporting Information.