分子铁电半导体及其光伏应用

Ferroelectric materials have become one of the most host research topics in photovoltaic field since they can produce an open-circuit voltage much larger than the band gap due to the anomalous photovoltaic effect. The molecular ferroelectric semiconductors have excellent ferroelectric and semiconducting properties. Additionally, they have some advance in low energy consume, low pollution, easy synthesis, and outstanding solution processability compared with inorganic ferroelectrics. These advantages make them a kind of very promising photovoltaic materials and have vast space for development in photovoltaic field. This project plans to synthesize molecular ferroelectric semiconductors based on organic-inorganic metal halides by using metal halides with semiconducting properties and organic ammonium salts as building blocks. Systematic characterizations including variable-temperature dielectric spectrum, variable-temperature structural analyses, polarization electricfield hysterisis loop, ultraviolet-visible spectrum, and conductivity will be performed to investigate their ferroelectric and semiconducting properties, in order to obtain molecular ferroelectric semiconductors with large spontaneous polarization, narrow band gap, and good conductivity. Then, we will prepare various photovoltaic devices based on these molecular ferroelectric semiconductor thin films and study the devices performance. The applications of molecular ferroelectric semiconductors in photovoltaic filed will provide a new idea for the development of photovoltaic filed and play a positive role in promoting the practical applications of molecular ferroelectrics.

铁电材料因其独特的反常光生伏打效应，能够产生远大于带隙的开路电压，成为光伏领域的研究热点。分子铁电半导体具有优越的铁电性质和半导体性质，与无机铁电材料相比还具有低能耗、更环保、易合成、易溶液加工等优点，是一类非常有前途的光伏材料，在光伏领域应用中具有广阔的发展空间和诱人的前景。本项目拟采用具有半导体性质的金属卤化物和有机铵盐作为构筑单元合成基于有机-无机杂化金属卤化物的分子铁电半导体。通过系统的表征包括变温介电谱、变温单晶结构、电滞回线、紫外可见光谱、电导率等研究其铁电性质和半导体性质，以获得自发极化较大、带隙较窄、导电性较好的分子铁电半导体。制备基于这些分子铁电半导体薄膜的各种光伏器件并研究器件性能。将分子铁电半导体作为光伏材料应用到光伏领域中，为光伏领域的发展提供了新思路，也为分子铁电体的实际应用起到积极的推动作用。

兼具铁电性和半导体特性的铁电半导体是一类重要的多功能材料。目前铁电半导体的研究主要集中在BiFeO3等无机铁电体，而具有柔性、轻量、易加工等优点的分子铁电体绝大多数是绝缘体，不具有半导体特性。本项目按项目任务书中内容计划实施，围绕分子铁电半导体研究，取得的重要研究成果包括：1、基于有机-无机杂化材料，合成了系列具有半导体特性等性质的分子相变化合物，为设计分子铁电半导体提供了思路；2、利用卤素取代分子修饰作用设计合成了带隙为2.82 eV的有机-无机杂化铅碘钙钛矿铁电半导体，并构筑了带隙低至1.95 eV、居里温度高达365 K的无铅有机-无机杂化铋碘分子铁电半导体，对新型分子铁电半导体的开发与研究具有重要的指导意义；3、将分子铁电半导体应用到了钙钛矿太阳能电池中，有效提高了器件性能，得到了较高的光电转换效率21.78%，为分子铁电半导体的光伏应用探索开辟了道路；4、此外，除了分子铁电半导体，也设计合成了单一手性分子铁电体和具有光致发光性质的反钙钛矿分子铁电体，将推动更多功能性分子铁电体的持续开发。在该项目的资助下，项目负责人以一作或通讯作者身份共计发表SCI论文24篇，其中影响因子大于3.0的文章22篇,包括J. Am. Chem. Soc. 3篇、Angew. Chem. Int. Ed. 1篇、Chem. Commun. 2篇、J. Mater. Chem. C 1篇、Dalton Trans. 4篇、Inorg. Chem. 2篇等。项目负责人入选了教育部“长江学者”青年学者奖励计划和第四届中国科协青年人才托举工程。