1：Experimental Design and Method Selection:

The study involves modifying the fabrication process of quasi-2D perovskite films (BA2MA3Pb4I13, n=4) by adding ethyl acetate as antisolvent, CH3NH3Cl (MACl), and dimethyl sulfoxide (DMSO) to control crystal growth direction and rate. Ultrafast transient absorption spectroscopy (fs-TA) is used to probe carrier dynamics, and steady-state UV-vis absorption, X-ray diffraction (XRD), and device fabrication (solar cells) are employed for characterization.

2：Sample Selection and Data Sources:

Films are prepared on glass substrates, with variations including pristine, antisolvent-treated, MACl-added, and DMSO-added samples. Data sources include absorption spectra, XRD patterns, and device performance metrics.

3：List of Experimental Equipment and Materials:

Equipment includes Agilent Cary 60 UV-vis spectrometer, PANalytical X-ray diffractometer, Bruker Dektak-XT stylus profiler, Keithley 2612B source meter, and a custom fs-TA setup with a Coherent Astrella laser and Light conversion optical parametric amplifier. Materials include BA2MA3Pb4I13 perovskite, DMF, DMSO, ethyl acetate, MACl, and substrates like FTO, SnO2, PEDOT:PSS, spiro-OMeTAD, PCBM, and gold for devices.

4：Experimental Procedures and Operational Workflow:

Precursor solutions are prepared and aged, spin-coated onto substrates, with antisolvent added during spinning for some samples. Films are annealed at 100°C. Characterization involves measuring absorption, XRD, and thickness. Devices are fabricated in conventional and inverted architectures. TA measurements are performed with front and back excitations at low pump power.

5：Data Analysis Methods:

Data analysis includes fitting kinetic traces from TA spectra to understand carrier transfer times, comparing absorption and XRD peaks for phase identification, and evaluating solar cell efficiency from J-V characteristics.