In alkyl ammonium lead halide based perovskites, the replacement of toxic Pb⁺² with a suitable nontoxic divalent metal cation without losing the photovoltaic performance is one of the prime challenges to the researchers. The understanding of the effect of replacing Pb⁺² on the structural and optical properties of alkyl ammonium lead halide based perovskites, and thereafter correlating their photovoltaic performances, comprise a fundamental study which is important towards developing efficient and non-toxic solar cells. In the present work, we used a wet chemical process to substitute Pb⁺² with Sn⁺² in different proportions into CH₃NH₃Pb_xSn_(1−x)Cl₃. The value of the Goldschmidt tolerance factor, which is a measure of structural stability of the perovskite lattice, was estimated theoretically. The theoretical calculations were correlated further with the experimentally obtained x-ray diffraction patterns of the original and substituted perovskites. The optical properties of CH₃NH₃Pb_(1−x)Sn_xCl₃ (0 ≤ x ≤ 1) perovskite thin-films were investigated by the ultraviolet–visible (UV–vis) absorption spectroscopy. The bandgap energy (E_g) for CH₃NH₃Pb_(1−x)Sn_xCl₃(0 ≤ x ≤ 1) were estimated from the optical absorption spectra. The Urbach energy (E_U) which predicts defects, disorder and crystalline imperfections within semiconducting thin-films were estimated for the prepared perovskite thin films. The steepness parameter which apprises about strength of electron–phonon (E_e–p) interaction within perovskites were also estimated from the optical absorbance spectra to understand the effect of replacing Pb⁺² with Sn⁺². In addition, the variations in the surface morphologies of the prepared perovskites were studied using scanning electron microscopy. The I–V characteristics of the different cells were analysed and, finally, we attempted to correlate their photovoltaic performances with the opto-structural properties.

在烷基铵卤化铅基钙钛矿中， 用合适的无毒二价金属阳离子代替有毒Pb ⁺²而又不损失光伏性能是研究人员面临的主要挑战之一。了解替代Pb ⁺² 对烷基铵卤化铅基钙钛矿的结构和光学性质的影响，然后关联其光伏性能，是一项基础研究，对于开发高效且无毒的太阳能电池至关重要。在目前的工作中，我们使用湿化学工艺以 不同比例将Pb ⁺² 与Sn ⁺²替换为CH ₃ NH ₃ Pb _x Sn _（1-x） Cl ₃。理论上估计了Goldschmidt耐受系数的值，该系数是钙钛矿晶格结构稳定性的量度。理论计算与原始钙钛矿和取代钙钛矿的实验X射线衍射图谱进一步相关。的光学性质CH ₃ NH ₃的Pb_{（1- X）}的Sn _X氯₃  （0≤  X  ≤1）的钙钛矿薄膜膜通过紫外-可见（UV-VIS）吸收光谱法研究。CH ₃ NH ₃ Pb_（1-的带隙能（ E _g）_X）的Sn _X氯₃（0≤  X  ≤1）是从光吸收谱估计。对于制备的钙钛矿薄膜，估计了预测半导体薄膜中的缺陷，无序和晶体缺陷的Urbach能量（ E _U）。钙钛矿中电子-声子（ E _e-p）相互作用强度的陡度参数也是根据光吸收光谱估算的，以了解 用Sn ⁺²代替Pb ⁺²的影响。另外，使用扫描电子显微镜研究了所制备的钙钛矿的表面形态的变化。分析了不同电池的IV特性，最后，我们尝试将其光伏性能与光电结构特性相关联。