Interplay of Guanidinium Doping and Structural Dynamics in FA‐Cs Perovskite Thin Film

ABSTRACT Perovskite solar cells (PSCs) have emerged as cutting‐edge technology in photovoltaic domain, offering a promising avenue for cost‐effective and efficient solar energy conversion. The use of guanidinium cation (GA + ) as A‐site dopant is demonstrated herein to modify the properties of FA‐Cs perovskite film, particularly FA 0.83 Cs 0.17 PbI 3 , resulting in an improved performance for photovoltaic applications. In this work, we aim to investigate the impact of GA doping on electronic, structural and optical properties of resultant perovskite material. The successful formation of perovskite structure has been confirmed by both X‐ray diffraction (XRD) and X‐ray photoelectron spectroscopy (XPS) techniques. The XRD results reveal that GA content plays a pivotal role in improving the film quality while suppressing the formation of residual PbI 2 precursor. Furthermore, the high absorbance and reduced band gap caused by GA doping have been investigated with the help of UV‐Vis spectroscopy. The surface chemistry and defect states of prepared perovskites are examined using XPS. The DFT simulations also validate the experimental findings, confirming electronic structure and band gap of the studied material. Our findings highlight the potential of GA‐doped FA‐Cs perovskite in revolutionizing the photovoltaic scenario, paving a path towards highly efficient, robust and next‐generation solar cells.