Recently, the iChEM researchers, Prof. Nanfeng Zheng and Prof. Yuanzhi Tan from Xiamen University, made important progress in the area of perovskite solar cell. The result was published in J. Am. Chem. Soc. as “Well-Defined Thiolated Nanographene as Hole-Transporting Material for Efficient and Stable Perovskite Solar Cells.” (J. Am. Chem. Soc. 2015, 137, 10914-10917).

The solution-processed hybrid perovskite solar cells (PSCs) have drawn dramatically increased attentions as a real competitor to silicon solar cell, due to their high power conversion efficiencies, easy fabrication and low-cost. Here, for the first time, a functionalized nanographene is employed as the hole transporting material (HTM) in PSCs, to achieve efficient charge extraction from perovskite by the Pb-S coordination interactions between nanographene with perovskite, and thus yield the best efficiency of 12.8% in pristine form. Furthermore, the efficiency is readily improved up to 14.0% by doping with graphene sheets into nanographene to enhance the charge transfer. By the HOMO-LUMO level engineering of TSHBC homologues. They also demonstrate that the HOMO levels are critical for the performance of PSCs. Moreover, beneficial from the hydrophobic nature of nanographene, the devices show the improved stability under AM 1.5 illumination in the humidity about 45% without encapsulation. These findings open the opportunities for efficient HTMs based on the functionalized nanographenes utilizing the strong interactions of their functional groups with perovskite.

This work was done under the co-guidance from Prof. Nanfeng Zheng and Prof. Yuanzhi Tan. The co-authors of this work are Ph.D student Jing Cao from Prof. Nanfeng Zheng' group (cell fabrication/test/characterization) and master student Yumin Liu from Prof. Yuanzhi Tan (material synthesis). The work was financially supported by the NSFC (21420102001, 21131005, 21390390, 21333008, 21401156) and the Ministry of Science and Technology of China (2011CB932403).

URL link for article: http://pubs.acs.org/doi/pdf/10.1021/jacs.5b06493