Fig. 1. Schematic of nanosecond TA and TRPL optical path

Fig. 2. Timing diagram of the high sensitive nanosecond TA spectrometer

Fig. 3. TA sensitivity test with the micro-pulse number of 20

Fig. 4. (a) Visible light absorption spectrum of MAPbI₃ film; (b) PL spectrum of MAPbI₃ thin film at room temperature under the excitation of laser with the wavelength of 516 nm and pulse energy of 2 nJ; (c) TRPL curve at the wavelength of 778 nm and the fitting result

Fig. 5. Testing result of MAPbI₃ thin films at 296 K. (a) TA spectra at different time delays under femtosecond laser excitation with an excitation wavelength of 517.5 nm, pulse energy of 50 nJ, and a spot diameter about 3 mm; (b) TA curves under detection wavelength of 758 nm and nanosecond pump laser pulses with energy of 4, 2, 1 nJ, and spot size of approximately 4 mm × 2.5 mm; (c) Fitting result for the pump pulse energy of 2 nJ

Fig. 6. Testing result of MAPbI₃ thin films at 220 K. (a) TA spectra at different time delays under femtosecond laser excitation wavelength of 517.5 nm, pulse energy of 50 nJ, and a spot diameter about 3 mm; (b) TA curves under detection wavelength of 771 nm and nanosecond pump laser pulses with energy of 4, 2, 1 nJ,and spot size of approximately 4 mm × 2.5 mm; (c) Fitting result for the pump pulse energy of 2 nJ