基于甲胺气体的固气反应制备高质量钙钛矿薄膜的研究

QIBEBT-IR > 仿生与固态能源系统研究组

	基于甲胺气体的固气反应制备高质量钙钛矿薄膜的研究
	王在伟
导师	逄淑平 ; 刘志宏
	2016-05
学位授予单位	中国科学院大学
学位授予地点	北京
学位专业	材料工程
关键词	钙钛矿太阳能电池甲胺气体甲胺铅碘碘化氢铅（hpbi3）
摘要	有机无机杂化钙钛矿材料具有合适的带隙宽度，较大的载流子扩散长度，大的消光系数，并可溶液法制备等优势，于是在光电领域吸引了科研工作者的广泛关注。2009年，有机无机杂化钙钛矿材料首次被应用于太阳能电池中，电池效率为3.8%，到目前已上升为22.1%。在短短几年内走完了多晶硅等太阳能电池几十年的发展历程，并且其便于大规模制备，成本低廉，展现出巨大的发展潜力和商业前景。钙钛矿太阳能电池效率的飞速提升，与钙钛矿的成膜工艺不断改善密切相关。目前常用的抗溶剂法和两步法等在制备小面积钙钛矿膜方面显示出一定优势，但制备高质量大面积钙钛矿太阳能电池仍面临一定的挑战。本文创造性的提出了一种便于大面积制备钙钛矿膜的甲胺气体缺陷修复技术（methylamine induced defect-healing，MIDH），并对其机理进行了深入研究和分析。我们首次发现室温下甲胺作用于甲胺铅碘（CH3NH3PbI3，MAPbI3）钙钛矿晶体，可以形成甲胺过量的甲胺铅碘液态相（CH3NH3PbI3•xCH3NH3(l)）,将其移出甲胺氛围，随着甲胺气体的挥发，甲胺铅碘重新结晶变成黑色甲胺铅碘固态相。基于这种室温固液可逆变化的现象，我们开发了甲胺气体缺陷修复技术制备致密均匀且结晶性良好的钙钛矿薄膜的工艺。钙钛矿太阳能电池的效率由修复前的5.7%上升为修复后的15.1%。并且这种成膜工艺便于大规模制备钙钛矿膜。同时，进一步对初始钙钛矿膜的形貌对MIDH技术的影响进行了研究，发现初始钙钛矿膜的形貌对最终修复后的钙钛矿膜形貌没有影响，这是因为不同初始钙钛矿膜经甲胺处理均得到了超平甲胺过量的甲胺铅碘液态相薄膜。这种气体作用下的固液可逆反应的现象属首次报道，将对材料学研究和材料成膜工艺的开发具有启发意义。在上述工作的基础上，考虑到两步溶液法中PbI2膜和CH3NH3I（MAI）反应困难的问题，我们设想通过引入全新的前驱体反应体系来从根本上改变传统两步溶液法反应困难的问题。通过分析MAPbI3的化学计量比，认为HPbI3作为无机相和CH3NH2（MA）气体作为有机相是一组可行的前驱体反应体系。我们研究发现，在室温下，MA气体可以在极短的时间（3 s）内和HPbI3无机相初始膜充分反应，制备出低粗糙度全覆盖的MAPbI3钙钛矿膜，得到的钙钛矿太阳能电池效率可达18.2%。这个过程中，相对于传统的PbI2和MAI前驱体体系，HPbI3和MA气体具有更强的酸碱相互作用，且在室温下HPbI3和MA作用生成了液态中间相，不存在固相扩散的过程，从而，从根本上解决了两步法钙钛矿反应困难的问题。
其他摘要	In the past few years, organo-lead halide perovskites (such as CH3NH3PbI3, MAPbI3 and NH2CH=NH2PbI3, FAPbI3) have drawn the attention of many scientists due to their attractive optical and electrical properties, together with their moderate cost and low temperature solution-process ability. These merits make them one of the most promising candidates for the industrial development of next-generation optoelectronic devices. The first reported solar cell employing CH3NH3PbI3 achieved an efficiency of 3.81% in 2009, and now, the certified record for power conversion efficiency (PCE) of PSCs stands at 22.1%. The increasing of efficiency of PSC is closely related to the improvement of perovskite film fabrication technology. The perovskite film fabrication technologies such as two-step solution method, antisolvent method and so on show advantages in little-area perovskite film, but there are also some hard challenges to prefer large-area perovskite solar cells. The paper reports the discovery of methylamine (CH3NH2) induced defect-healing (MIDH) of CH3NH3PbI3 perovskite thin films based on their ultrafast (seconds), reversible chemical reaction with CH3NH2 gas at room temperature. The key to this healing behavior is the formation and spreading of an intermediate CH3NH3PbI3·xCH3NH2 liquid phase during this unusual perovskite–gas interaction. We demonstrate the versatility and scalability of the MIDH process, and show dramatic enhancement in the performance of perovskite solar cells (PSCs) with MIDH. This study represents a new direction in the formation of defect-free films of hybrid perovskites. To gain further insight into this gas–perovskite interaction behavior, the effects of the morphology of the starting films are studied. The results demonstrate that raw MAPbI3 perovskite films with different types of common “defective” morphologies can be healed to nearly the same “perfect” state using MIDH. Based on this work, inspection of the stoichiometry of MAPbI3 suggests that a new possible precursor pair consisting of hydrogen lead triiodide (HPbI3) as the inorganic component and methylamine gas (CH3NH2) as the organic component may be promise for the deposition of high-quality MAPbI3 perovskite thin films for high-PCE PSCs. We have observed that a strong room-temperature solid−gas interaction behavior between the HPbI3-CH3NH2 precursor pair results in ultrasmooth, full coverage MAPbI3 perovskite thin films, which is virtually independent of the poor morphology of the starting HPbI3 precursor films, making this deposition process highly robust. The chemical origins responsible for the transformative evolution of MAPbI3 perovskite thin films are elucidated. This study highlights the significance of precursor interaction chemistry in the formation of high-quality hybrid perovskite thin films, which is playing a central role in the scalable production of high-PCE PSCs of the future.
作者部门	仿生能源与储能系统团队
学科领域	太阳能电池
公开日期	2016-07-01
学位类型	硕士 ; 学位论文
语种	中文
文献类型	学位论文
条目标识符	http://ir.qibebt.ac.cn/handle/337004/9782
专题	仿生与固态能源系统研究组
作者单位	中国科学院青岛生物能源与过程研究所
推荐引用方式 GB/T 7714	王在伟. 基于甲胺气体的固气反应制备高质量钙钛矿薄膜的研究[D]. 北京. 中国科学院大学,2016.

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