Wang Miao, Yu Qiyu, Yu Tian, Zhang Sijie, Gong Min, Liu Yuehui
College of Physics, Sichuan University Chengdu 610065 China.
College of Material Science and Engineering, Sichuan University of Science and Engineering Zigong 643000 China
RSC Adv. 2023 Feb 9;13(8):5158-5167. doi: 10.1039/d2ra06491j. eCollection 2023 Feb 6.
To realize the precise modulation among the cesium lead halide perovskite-related phases is one of the most fascinating subjects and has motivated increasing research. The formation mechanisms of different phases of cesium lead halide have not been fully recognized. In this work, we reported the phase-selective synthesis of CsPbBr nanorods and CsPbBr nanocrystals (NCs) in amine-free systems, simply by adjusting the dosage of oleic acid (OA). By utilizing UV-visible absorption spectroscopy, we probed the evolution of the NCs and some lead bromide complex species during syntheses in reaction systems with different OA dosages. An OA-limited condition facilitated the formation of [PbBr] and CsPbBr NCs. OA-rich conditions facilitated the formation of [PbBr], [PbBr], at early stages and the subsequent generation of CsPbBr NCs. As the reaction systems equilibrated at a later stage, as-prepared CsPbBr or CsPbBr NCs would coexist with certain lead bromide complexes. OA dosage also greatly affected the kinetics of reactions toward CsPbBr NCs. A relatively large amount of OA would accelerate the formation of CsPbBr NCs. Our experimental results support two-step formation pathways of the cesium lead bromide NCs going through lead bromide complexes, and suggest that OA exerted all the influence by virtue of the lead bromide complexes. Our study presents a relatively clear picture of the formation of CsPbBr and CsPbBr NCs, which should be helpful in improving the preparation of lead halide perovskite-related NCs.
实现卤化铯铅钙钛矿相关相之间的精确调控是最引人入胜的课题之一，并激发了越来越多的研究。卤化铯铅不同相的形成机制尚未得到充分认识。在这项工作中，我们报道了在无胺体系中通过简单调节油酸（OA）用量实现CsPbBr纳米棒和CsPbBr纳米晶体（NCs）的相选择性合成。利用紫外可见吸收光谱，我们探测了在不同OA用量的反应体系中合成过程中NCs和一些溴化铅络合物物种的演变。OA受限条件促进了[PbBr]和CsPbBr NCs的形成。富OA条件在早期促进了[PbBr]、[PbBr]的形成以及随后CsPbBr NCs的生成。随着反应体系在后期达到平衡，所制备的CsPbBr或CsPbBr NCs将与某些溴化铅络合物共存。OA用量也极大地影响了生成CsPbBr NCs的反应动力学。相对大量的OA会加速CsPbBr NCs的形成。我们的实验结果支持卤化铯铅NCs通过溴化铅络合物的两步形成途径，并表明OA凭借溴化铅络合物发挥了所有影响。我们的研究给出了CsPbBr和CsPbBr NCs形成的相对清晰的图景，这应该有助于改进卤化铅钙钛矿相关NCs的制备。
