1：Experimental Design and Method Selection:

The study involved the synthesis of reduced graphene oxide (rGO) and its incorporation into the TiO2 electron transport layer (ETL), the CH3NH3PbI3 perovskite absorber, and the Spiro-MeOTAD hole transporter of planar perovskite solar cells (PSCs). The effects of rGO on the photovoltaic performance and stability of PSCs were investigated.

2：Sample Selection and Data Sources:

The samples included PSCs with and without rGO in their components. Data were collected through various characterization techniques including TEM, UV-vis spectroscopy, Raman spectroscopy, XRD, SEM, AFM, PL measurements, and J-V measurements.

3：List of Experimental Equipment and Materials:

Equipment used included a TEM (FEI CM20), UV-Vis spectrometer (Hitachi 3010), Raman microscope (Renishaw in Via Reflex), XRD (Siemens D-500), SEM (JSM 7401F), AFM (Digital Instruments Nanoscope III), and a solar simulator (Model 16S-300). Materials included graphite oxide, hydriodic acid, acetic acid, titanium (IV) isopropoxide, methylammonium iodide, lead acetate trihydrate, and Spiro-MeOTAD.

4：0). Materials included graphite oxide, hydriodic acid, acetic acid, titanium (IV) isopropoxide, methylammonium iodide, lead acetate trihydrate, and Spiro-MeOTAD. Experimental Procedures and Operational Workflow:

4. Experimental Procedures and Operational Workflow: The rGO was synthesized via a modified Hummers’ method and incorporated into the PSC components. The PSCs were fabricated by spin-coating the layers on FTO substrates, followed by annealing and electrode deposition. Characterization was performed to assess the morphology, crystallinity, and photovoltaic performance.

5：Data Analysis Methods:

Data were analyzed using statistical methods to compare the performance of PSCs with and without rGO. The photovoltaic parameters (Jsc, Voc, FF, PCE) were extracted from J-V curves, and the stability was assessed over time.