Wavelength Dependent Light-Induced Degradation of Perovskite Solar Cells

Recently, perovskite solar cells (PSCs) are about to be commercialized due to their high power conversion efficiency and ease of fabrication. However, despite their high efficiency and excellent properties, there remain many challenges in the commercialization of perovskite solar cells primarily due to the low intrinsic stability of perovskite materials. Therefore, research on stability requires a lot of attention, with major factors undermining the stability of PSCs including moisture and oxygen, light, electrical bias, heat, and mechanical degradation.<br/><br/>Among the origin of perovskite degradation, elucidating the mechanism of light-induced degradation is critical since it is inevitable to irradiate the light to operate PSCs. Previous studies suggest that the interaction between trapped charge carriers and surrounding gas-phase molecules (oxygen and moisture) contributes to the degradation of the perovskite materials, and hole carriers are more particularly detrimental to this degradation process. In PSC, these charge carriers are generated by the broad wavelength solar irradiation. If perovskite materials degrade more significantly within specific wavelengths, blocking those wavelengths could enhance the long-term stability of PSCs.<br/><br/>Existing studies have suggested the degree of degradation of PSCs by wavelength with the identical intensity of the light irradiated through photodiodes or using band-pass filters from the same light source. In these studies, though the intensity of the irradiated light was identical, the number of generated charge carriers was not assured to be equal. Therefore, it was not clearly distinguished whether the difference in the degree of degradation was due to the wavelength of the light or the number of charge carriers.<br/><br/>Therefore, this study aims to evaluate the degree of degradation by wavelength (red = 610–800 nm, green = 500–590 nm, and blue = 300–500 nm) using band-pass filters while unifying the number of charge carriers generated in PSCs without maintaining the intensity of the irradiated light, adjusting the light intensity according to the number of charge carriers in an inert environment.