Effect of FABr Passivation on the Interface of Perovskite/hole-transporting Layer on Perovskite Solar Cells with Donor-Acceptor Conjugated Polymer
Nobuko Onozawa-Komatsuzaki a, Yoshihiko Nishihara a b, Masayuki Chikamatsu a, Yuji Yoshida a b
a National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, 1-1-1 Higashi, Ibaraki, Japan
b University of Tsukuba
Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics
Proceedings of Asia-Pacific International Conference on Perovskite, Organic Photovoltaics and Optoelectronics (IPEROP20)
Tsukuba-shi, Japan, 2020 January 20th - 22nd
Organizers: Michio Kondo and Takurou Murakami
Poster, Nobuko Onozawa-Komatsuzaki, 087
Publication date: 14th October 2019

Solution-processed hybrid perovskite solar cells (PSCs) have attracted considerable attention as a promising alternative for solar cells due to their high-power conversion efficiencies, easy fabrication, and low cost. Therefore, to achieve the practical use of PSCs, investigations have been conducted from various perspectives. A key component of PSCs is the hole-transporting layer (HTL), which plays a crucial role in achieving high performance by reducing charge recombination. Recently, several attempts have been made to demonstrate the potential of conjugated polymers as HTLs. In these conjugated polymer HTLs, frontier energy levels are controlled via modifying the side chain and substituting atoms in the aromatic rings. As a result, the compatibility of band alignment and the stability are improved.

In this study, we investigated a donor-acceptor conjugated polymer, poly[(2,5-bis(2-hexyldecyloxy)-phenylene)-alt-(5,6-difluoro-4,7-di(thiophen-2-yl)benzo[c]-[1,2,5]-thiadiazole)] (PPDT2FBT)[1], as a HTL in PSCs. The overall power conversion efficiency of PSCs with PPDT2FBT as a HTL decreased compare to that of standard PSCs with spiro-OMeTAD. We introduced a surface passivation layer by spin-coating a formamidinium bromide (FABr) solution on an as-prepared perovskite film with the presence of excess PbI2.[2] PSCs treated with FABr solution showed higher open-circuit voltage and fill factor than those of untreated cells. This result indicates that the passivation layer prevents a backflow of holes from a HTL to the perovskite to suppress charge recombination.

This research was funded by the New Energy and Industrial Technology Development Organization (NEDO).

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