Synthesis of Diketopyrrolopyrrole-thiophene Polymers bearing Thermally-cleavable Boc group and their Application to All-inorganic Perovskite Solar Cells
Teruhiro Fukushima a, Kenichi Oyaizu a, Hiroyuki Nishide a, Takeo Suga a
a Department of Applied Chemistry and Research Institute for Science and Engineering, Waseda University, 169-8555, Japan
Poster, Teruhiro Fukushima, 071
Publication date: 21st November 2022

Poly(3-hexylthiophene) (P3HT) has attracted much research attention as a hole-transporting material for organic transistors and organic photovoltaics. High hole mobility without any dopants, high crystallinity, and good solubility of P3HT are also promising characteristics for an all-inorganic perovskite (CsPbI2Br)-based solar cell. However, energy loss in VOC is a challenging task to improve photoelectric conversion efficiency (PCE). In this report, we introduce diketopyrrolopyrrole units into thiophene-based polymers as an acceptor moiety to match their HOMO levels with a deep valence band (-5.5 eV) of CsPbI2Br. Furthermore, we installed a thermally-cleavable tert-butoxycarbonyl (t-Boc) group into the diketopyrrolopyrrole units to tune the solubility of the polymer. The obtained polymer showed a deeper HOMO level (-5.2 eV) than that of P3HT, and show solubility switching with a weight loss of t-Boc group under thermal treatment (200°C). We utilized the polymer to a hole-injection layer as an interface of CsPbI2Br and P3HT to improve PCE.

This work was partially supported by NEDO project (20001016-0).

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