Ferroelectric Graphene鈥揚erovskite Interfaces

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• 作者：George Volonakis ; Feliciano Giustino
• 刊名：The Journal of Physical Chemistry Letters
• 出版年：2015
• 出版时间：July 2, 2015
• 年：2015
• 卷：6
• 期：13
• 页码：2496-2502
• 全文大小：435K
• ISSN：1948-7185

文摘

Owing to their record-breaking energy conversion efficiencies, hybrid organometallic perovskites have emerged as the most promising light absorbers and ambipolar carrier transporters for solution-processable solar cells. Simultaneously, due to its exceptional electron mobility, graphene represents a prominent candidate for replacing transparent conducting oxides. Thus, it is possible that combining these wonder materials may propel the efficiency toward the Schokley鈥換ueisser limit. Here, using first-principles calculations on graphene鈥揅H₃NH₃PbI₃ interfaces, we find that graphene suppresses the octahedral tilt in the very first perovskite monolayer, leading to a nanoscale ferroelectric distortion with a permanent polarization of 3 mC/m². This interfacial ferroelectricity drives electron extraction from the perovskite and hinders electron鈥揾ole recombination by keeping the electrons and holes separated. The interfacial ferroelectricity identified here simply results from the interplay between graphene鈥檚 planar structure and CH₃NH₃PbI₃鈥檚 octahedral connectivity; therefore, this mechanism may be effective in a much broader class of perovskites, with potential applications in photovoltaics and photocatalysis.