We have designed and synthesized fluorinated indolo[3,2-b]indole (IDID) derivatives as crystalline hole-transporting materials (HTM) for perovskite solar cells. The fluorinated IDID backbone enables a tight molecular arrangement stacked by strong π-π interactions, leading to a higher hole mobility than that of the current HTM standard, p,p-spiro-OMeTAD, with a spherical shape and amorphous morphology. Moreover, the photoluminescence quenching in a perovskite/HTM film is more effective at the interface of the perovskite with IDIDF as compared to that of p,p-spiro-OMeTAD. As a consequence, the device fabricated using IDIDF shows superior photovoltaic properties compared to that using p,p-spiro-OMeTAD, exhibiting an optimal performance of 19%. Thus, this remarkable result demonstrates IDID core-based materials as a new class of HTMs for highly efficient perovskite solar cells.
Bibliographical noteFunding Information:
This work was supported by the National Research Foundation of Korea (NRF) through a grant funded by the Korean Government (MSIP; No. 2009-0081571[RIAM0417-20150013]) and the Global Frontier R&D Program at the Center for Multiscale Energy Systems funded by the National Research Foundation under the Ministry of Science, ICT & Future Planning, Korea (2012M3A6A7055540) (Global Frontier R&D Program on Center for Multiscale Energy System) and NRF-2015M1A2A2056542. This work was also supported by a grant from the Korea Research Institute of Chemical Technology (KRICT), Republic of Korea (KK1602-A01). N. J. Jeon also acknowledges support by the Basic Science Research Program through the NRF, funded by the Ministry of Education (NRF-2015R1A6A3A04058164)
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