Masawa Salma Maneno, Li Jihong, Zhao Chenxu, Liu Xiaolong, Yao Jianxi
Beijing Key Laboratory of Energy Safety and Clean Utilization, North China Electric Power University, Beijing 102206, China.
Department of Petroleum and Energy Engineering, College of Earth Sciences and Engineering, The University of Dodoma, Dodoma P.O. Box 259, Tanzania.
Materials (Basel). 2022 Mar 16;15(6):2180. doi: 10.3390/ma15062180.
Bismuth-based perovskites are potentially a promising alternative for lead-free perovskites. During bond formation, however, trivalent ions on Cs3Bi2I9 with CsI/BiI3 ratio of 1.5/1 form 0D-neutral charged compounds with higher bandgap (>2.0 eV) and poor absorption capacity. Mixed 0/2-dimensional structures are potentially suitable substitutes due to their low bandgap. So far, the reported CsI/BiI3 ratios for 0D/2D structures are 1:1, 1:2 and 1:3. Herein, a new ratio of 1/1.5 is reported. Caesium bismuth iodide at a ratio of CsI/BiI3 of 1/1.5 was synthesised using a one-step processing method with/without solvent vapour annealing. During solvent annealing, a 1/4 (v/v) mixture of DMF/methanol was used as a solvent. The crystal structure formed at a ratio of 1/1.5 is more similar to 1.5/1 than to 1/3. The XRD pattern revealed additional characteristics peaks at 009, 012, 209 and 300, indicating the growth of another phase. The formed heterogeneous mixed 0D/2D structure has an extended light absorption capacity greater than 720 nm. Solvent vapour annealing improved film morphology by enhancing grain size and packing density. When cells with and without solvent vapour annealing are compared, the power conversion efficiency of caesium bismuth iodide increases from 0.26% without solvent annealing to 0.98% with solvent vapour annealing. This study establishes a new route for future research on crystal configuration, nomenclature, film and morphology, quality tailoring and applications toward the goal of lead-free perovskite solar cells.
铋基钙钛矿有可能成为无铅钙钛矿的一种有前景的替代材料。然而，在成键过程中，CsI/BiI₃ 比例为 1.5/1 的 Cs₃Bi₂I₉ 上的三价离子形成了具有更高带隙（>2.0 eV）和较差吸收能力的零维中性带电化合物。混合的 0/2 维结构因其低带隙而有可能成为合适的替代材料。到目前为止，报道的 0D/2D 结构的 CsI/BiI₃ 比例为 1:1、1:2 和 1:3。在此，报道了一种新的 1/1.5 的比例。采用一步法并在有/无溶剂蒸汽退火的条件下，合成了 CsI/BiI₃ 比例为 1/1.5 的碘化铯铋。在溶剂退火过程中，使用 DMF/甲醇的 1/4（v/v）混合物作为溶剂。以 1/1.5 的比例形成的晶体结构与 1.5/1 的结构比与 1/3 的结构更相似。XRD 图谱在 009、012、209 和 300 处显示出额外的特征峰，表明形成了另一相。所形成的异质混合 0D/2D 结构具有大于 720 nm 的扩展光吸收能力。溶剂蒸汽退火通过提高晶粒尺寸和堆积密度改善了薄膜形态。当比较有和没有溶剂蒸汽退火的电池时，碘化铯铋的功率转换效率从没有溶剂退火时的 0.26%提高到有溶剂蒸汽退火时的 0.98%。本研究为未来关于晶体构型、命名、薄膜和形态、质量剪裁以及朝着无铅钙钛矿太阳能电池目标的应用研究建立了一条新途径。
